Merge bitcoin/bitcoin#25861: guix: use --build={arch}-guix-linux-gnu in cross toolchain

56e79fe guix: use --build={arch}-guix-linux-gnu in cross toolchain (fanquake)

Pull request description:

  Technically we are always cross-compiling when Guix building, so make that explicit. `{arch}-guix-linux-gnu` is not a triplet that should be used in any other capacity, but here it serves the purpose of ensuring, that by setting `--build` to something other than `--host/--target`, we are always cross-compiling (in the eyes of autoconf etc) when building our cross toolchains. It looks like `x86_64-linux-gnu` on `x86_64-linux-gnu` currently works because of the triplet canonicalisation, i.e `x86_64-linux-gnu` becomes `x86_64-pc-linux-gnu`, and GCCs configure thinking it's cross-compiling, whereas the same canonicalisation doesn't happen for `aarch64-linux-gnu` so we don't get a cross-compile when building on aarch64.

  Fixes: #22458.

  Guix Build (x86_64):
  ```bash
  e590e67d2b151e7d079f50393c61cacf9e65f5e3fdddc10bffd5dbb59cd9f5e3  guix-build-56e79fe683d3/output/aarch64-linux-gnu/SHA256SUMS.part
  9222a733209dc73168722ee0f290831d1723f7ed55abc1e243dd3892ef9733f1  guix-build-56e79fe683d3/output/aarch64-linux-gnu/bitcoin-56e79fe683d3-aarch64-linux-gnu-debug.tar.gz
  a4ec01411195412e9a483397554d98b2db161a6be8aceee2dac78f0015f2a8e5  guix-build-56e79fe683d3/output/aarch64-linux-gnu/bitcoin-56e79fe683d3-aarch64-linux-gnu.tar.gz
  a4ff8f2538c1b3a63a3e7c92699c18164b2c4954ebd72c4a854bf7844e6131b6  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/SHA256SUMS.part
  ac6e4dffcf6f49dac73d3677f3fe5edb08ee1127648bc7ec24b217f48a3a4d21  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/bitcoin-56e79fe683d3-arm-linux-gnueabihf-debug.tar.gz
  ab26467fce9732596b1713179618eee20c2bd44875dc1c39f9afd68f135e8ce4  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/bitcoin-56e79fe683d3-arm-linux-gnueabihf.tar.gz
  f44108d818d53ee7e70b44361cb3cc6841b7aecbe4fade1fa289263718620824  guix-build-56e79fe683d3/output/arm64-apple-darwin/SHA256SUMS.part
  29adfb2d575be8b5a7092b2aff888af2084ad5783bdc74ae3de4b2dd84da7a26  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin-unsigned.dmg
  3d7640f604bd27cb1ae47853d70378a7631aa436b5c027eae31fa06d4dd20d4a  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin-unsigned.tar.gz
  3f8d8fc49cf722a7a13640872762d045c14efd610fba908f0acc99a99032b903  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin.tar.gz
  b8df097e10e7acded8556a5681da2b0132c0d509b200792f5584c186b8dcaf24  guix-build-56e79fe683d3/output/dist-archive/bitcoin-56e79fe683d3.tar.gz
  1a605c563038107b88e8d859fa045ca3087241340264eb7125e97b3af36874db  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/SHA256SUMS.part
  d10be89a816ee2f47bf778ef4aaa8a7b548403c123a4b4b3aa0470ee7b9472d2  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/bitcoin-56e79fe683d3-powerpc64-linux-gnu-debug.tar.gz
  839dd079d677c87a91ccc28f6c423657d98212350d3693ae2facb92082d10c88  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/bitcoin-56e79fe683d3-powerpc64-linux-gnu.tar.gz
  200d7a72a7901b6788e70aa1c6fbbe16144e9dac29beb06242a9dcfe1e88acbe  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/SHA256SUMS.part
  3d207bb57dc45f234d804a9ee615001aa28ac4b59b530a1e7d16d0a72c2ea514  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/bitcoin-56e79fe683d3-powerpc64le-linux-gnu-debug.tar.gz
  16a789c98409d36bd6b69a5ca38cd8886979f50f845265dc0b005c92286a3e4f  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/bitcoin-56e79fe683d3-powerpc64le-linux-gnu.tar.gz
  e48f6fae9c2ffeb2bf02ffc073ac69648b2ce4ba87e0ad7a3a5059abf33b8ce2  guix-build-56e79fe683d3/output/riscv64-linux-gnu/SHA256SUMS.part
  fa8d66af5f202e0c8968114af4dcd6d88099eb91d197dfaaa0144f8ae6b12f4a  guix-build-56e79fe683d3/output/riscv64-linux-gnu/bitcoin-56e79fe683d3-riscv64-linux-gnu-debug.tar.gz
  86cffa62687f4272c899897ff6c1a86e1a7bdbbb7ab09a085b7b1122d3a1f1b2  guix-build-56e79fe683d3/output/riscv64-linux-gnu/bitcoin-56e79fe683d3-riscv64-linux-gnu.tar.gz
  e42a7c33da6ea4be5d0826df097bdc7e919c9fd6642e7d59fe3d45a97d9009fa  guix-build-56e79fe683d3/output/x86_64-apple-darwin/SHA256SUMS.part
  2f9faa88fa0025b9bfade83177b1f50833dc6c3be1ef26c4d5881aa165bcc537  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin-unsigned.dmg
  fdfe560968c85500dc886d4e12b851cd27a76de860b8cbf1fb6aac95ccd0582e  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin-unsigned.tar.gz
  c3c75560befd72a9f13f5626ddf39c63ad25fb9753a4d941e48830b7e06f143e  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin.tar.gz
  38100946ec1469fdd31aa8ea9e471b317dc278c298c106289c119016c2c0caa0  guix-build-56e79fe683d3/output/x86_64-linux-gnu/SHA256SUMS.part
  67890771aad89dc0d20b8dcdc6b29bd838ace310e8bcbbc0d16d7afc87d3a474  guix-build-56e79fe683d3/output/x86_64-linux-gnu/bitcoin-56e79fe683d3-x86_64-linux-gnu-debug.tar.gz
  a9772b40c8b9d3c1a0bf9c9db2a60050415bf6a9bd4a19cfd8a038f4a1e712e3  guix-build-56e79fe683d3/output/x86_64-linux-gnu/bitcoin-56e79fe683d3-x86_64-linux-gnu.tar.gz
  01da0561f2c3a268c28615b1573dfdecb6346bf3f8eba7a052488191234ac1d6  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/SHA256SUMS.part
  71324ac0f6fc8163e41031b2fd2d38d2e15bfd5ef4efe4cb45d7974fad474394  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-debug.zip
  219b58281d3c79b2ed7e9085b1e15d7e021fd3899ef07a6ad747058b43d64443  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-setup-unsigned.exe
  fe838d32587c2f942fcd9f9a0b3735611b686a867e2d2040cf3a8aa6a43d09fe  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-unsigned.tar.gz
  13b537217a13293b93afd7c588b3733955c3188f79a3249b363fb4e885b74b32  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64.zip
  ```

  Guix Build (arm64):
  ```bash
  e590e67d2b151e7d079f50393c61cacf9e65f5e3fdddc10bffd5dbb59cd9f5e3  guix-build-56e79fe683d3/output/aarch64-linux-gnu/SHA256SUMS.part
  9222a733209dc73168722ee0f290831d1723f7ed55abc1e243dd3892ef9733f1  guix-build-56e79fe683d3/output/aarch64-linux-gnu/bitcoin-56e79fe683d3-aarch64-linux-gnu-debug.tar.gz
  a4ec01411195412e9a483397554d98b2db161a6be8aceee2dac78f0015f2a8e5  guix-build-56e79fe683d3/output/aarch64-linux-gnu/bitcoin-56e79fe683d3-aarch64-linux-gnu.tar.gz
  a4ff8f2538c1b3a63a3e7c92699c18164b2c4954ebd72c4a854bf7844e6131b6  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/SHA256SUMS.part
  ac6e4dffcf6f49dac73d3677f3fe5edb08ee1127648bc7ec24b217f48a3a4d21  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/bitcoin-56e79fe683d3-arm-linux-gnueabihf-debug.tar.gz
  ab26467fce9732596b1713179618eee20c2bd44875dc1c39f9afd68f135e8ce4  guix-build-56e79fe683d3/output/arm-linux-gnueabihf/bitcoin-56e79fe683d3-arm-linux-gnueabihf.tar.gz
  f44108d818d53ee7e70b44361cb3cc6841b7aecbe4fade1fa289263718620824  guix-build-56e79fe683d3/output/arm64-apple-darwin/SHA256SUMS.part
  29adfb2d575be8b5a7092b2aff888af2084ad5783bdc74ae3de4b2dd84da7a26  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin-unsigned.dmg
  3d7640f604bd27cb1ae47853d70378a7631aa436b5c027eae31fa06d4dd20d4a  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin-unsigned.tar.gz
  3f8d8fc49cf722a7a13640872762d045c14efd610fba908f0acc99a99032b903  guix-build-56e79fe683d3/output/arm64-apple-darwin/bitcoin-56e79fe683d3-arm64-apple-darwin.tar.gz
  b8df097e10e7acded8556a5681da2b0132c0d509b200792f5584c186b8dcaf24  guix-build-56e79fe683d3/output/dist-archive/bitcoin-56e79fe683d3.tar.gz
  1a605c563038107b88e8d859fa045ca3087241340264eb7125e97b3af36874db  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/SHA256SUMS.part
  d10be89a816ee2f47bf778ef4aaa8a7b548403c123a4b4b3aa0470ee7b9472d2  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/bitcoin-56e79fe683d3-powerpc64-linux-gnu-debug.tar.gz
  839dd079d677c87a91ccc28f6c423657d98212350d3693ae2facb92082d10c88  guix-build-56e79fe683d3/output/powerpc64-linux-gnu/bitcoin-56e79fe683d3-powerpc64-linux-gnu.tar.gz
  200d7a72a7901b6788e70aa1c6fbbe16144e9dac29beb06242a9dcfe1e88acbe  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/SHA256SUMS.part
  3d207bb57dc45f234d804a9ee615001aa28ac4b59b530a1e7d16d0a72c2ea514  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/bitcoin-56e79fe683d3-powerpc64le-linux-gnu-debug.tar.gz
  16a789c98409d36bd6b69a5ca38cd8886979f50f845265dc0b005c92286a3e4f  guix-build-56e79fe683d3/output/powerpc64le-linux-gnu/bitcoin-56e79fe683d3-powerpc64le-linux-gnu.tar.gz
  e48f6fae9c2ffeb2bf02ffc073ac69648b2ce4ba87e0ad7a3a5059abf33b8ce2  guix-build-56e79fe683d3/output/riscv64-linux-gnu/SHA256SUMS.part
  fa8d66af5f202e0c8968114af4dcd6d88099eb91d197dfaaa0144f8ae6b12f4a  guix-build-56e79fe683d3/output/riscv64-linux-gnu/bitcoin-56e79fe683d3-riscv64-linux-gnu-debug.tar.gz
  86cffa62687f4272c899897ff6c1a86e1a7bdbbb7ab09a085b7b1122d3a1f1b2  guix-build-56e79fe683d3/output/riscv64-linux-gnu/bitcoin-56e79fe683d3-riscv64-linux-gnu.tar.gz
  e42a7c33da6ea4be5d0826df097bdc7e919c9fd6642e7d59fe3d45a97d9009fa  guix-build-56e79fe683d3/output/x86_64-apple-darwin/SHA256SUMS.part
  2f9faa88fa0025b9bfade83177b1f50833dc6c3be1ef26c4d5881aa165bcc537  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin-unsigned.dmg
  fdfe560968c85500dc886d4e12b851cd27a76de860b8cbf1fb6aac95ccd0582e  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin-unsigned.tar.gz
  c3c75560befd72a9f13f5626ddf39c63ad25fb9753a4d941e48830b7e06f143e  guix-build-56e79fe683d3/output/x86_64-apple-darwin/bitcoin-56e79fe683d3-x86_64-apple-darwin.tar.gz
  38100946ec1469fdd31aa8ea9e471b317dc278c298c106289c119016c2c0caa0  guix-build-56e79fe683d3/output/x86_64-linux-gnu/SHA256SUMS.part
  67890771aad89dc0d20b8dcdc6b29bd838ace310e8bcbbc0d16d7afc87d3a474  guix-build-56e79fe683d3/output/x86_64-linux-gnu/bitcoin-56e79fe683d3-x86_64-linux-gnu-debug.tar.gz
  a9772b40c8b9d3c1a0bf9c9db2a60050415bf6a9bd4a19cfd8a038f4a1e712e3  guix-build-56e79fe683d3/output/x86_64-linux-gnu/bitcoin-56e79fe683d3-x86_64-linux-gnu.tar.gz
  01da0561f2c3a268c28615b1573dfdecb6346bf3f8eba7a052488191234ac1d6  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/SHA256SUMS.part
  71324ac0f6fc8163e41031b2fd2d38d2e15bfd5ef4efe4cb45d7974fad474394  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-debug.zip
  219b58281d3c79b2ed7e9085b1e15d7e021fd3899ef07a6ad747058b43d64443  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-setup-unsigned.exe
  fe838d32587c2f942fcd9f9a0b3735611b686a867e2d2040cf3a8aa6a43d09fe  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64-unsigned.tar.gz
  13b537217a13293b93afd7c588b3733955c3188f79a3249b363fb4e885b74b32  guix-build-56e79fe683d3/output/x86_64-w64-mingw32/bitcoin-56e79fe683d3-win64.zip
  ```

ACKs for top commit:
  hebasto:
    ACK 56e79fe

Tree-SHA512: 628ab6cda80069ad277107639bef21b44a8417198862e9ec89b45a2c41741d29aeb79aa58c5a90283fb96cf707494ae948ac790abde809bb18c86b14af999200

Author: fanquake

contrib/guix/manifest.scm

@@ -78,6 +78,11 @@ http://www.linuxfromscratch.org/hlfs/view/development/chapter05/gcc-pass1.html"
                  (("-rpath=") "-rpath-link="))
                #t))))))))
 
+(define building-on (string-append (list-ref (string-split (%current-system) #\-) 0) "-guix-linux-gnu"))
+
+(define (explicit-cross-configure package)
+  (package-with-extra-configure-variable package "--build" building-on))
+
 (define (make-cross-toolchain target
                               base-gcc-for-libc
                               base-kernel-headers
@@ -87,9 +92,9 @@ http://www.linuxfromscratch.org/hlfs/view/development/chapter05/gcc-pass1.html"
   (let* ((xbinutils (cross-binutils target))
          ;; 1. Build a cross-compiling gcc without targeting any libc, derived
          ;; from BASE-GCC-FOR-LIBC
-         (xgcc-sans-libc (cross-gcc target
-                                    #:xgcc base-gcc-for-libc
-                                    #:xbinutils xbinutils))
+         (xgcc-sans-libc (explicit-cross-configure (cross-gcc target
+                                                              #:xgcc base-gcc-for-libc
+                                                              #:xbinutils xbinutils)))
          ;; 2. Build cross-compiled kernel headers with XGCC-SANS-LIBC, derived
          ;; from BASE-KERNEL-HEADERS
          (xkernel (cross-kernel-headers target
@@ -98,17 +103,17 @@ http://www.linuxfromscratch.org/hlfs/view/development/chapter05/gcc-pass1.html"
                                         xbinutils))
          ;; 3. Build a cross-compiled libc with XGCC-SANS-LIBC and XKERNEL,
          ;; derived from BASE-LIBC
-         (xlibc (cross-libc target
-                            base-libc
-                            xgcc-sans-libc
-                            xbinutils
-                            xkernel))
+         (xlibc (explicit-cross-configure (cross-libc target
+                                                      base-libc
+                                                      xgcc-sans-libc
+                                                      xbinutils
+                                                      xkernel)))
          ;; 4. Build a cross-compiling gcc targeting XLIBC, derived from
          ;; BASE-GCC
-         (xgcc (cross-gcc target
-                          #:xgcc base-gcc
-                          #:xbinutils xbinutils
-                          #:libc xlibc)))
+         (xgcc (explicit-cross-configure (cross-gcc target
+                                                    #:xgcc base-gcc
+                                                    #:xbinutils xbinutils
+                                                    #:libc xlibc))))
     ;; Define a meta-package that propagates the resulting XBINUTILS, XLIBC, and
     ;; XGCC
     (package