Discover target triple

The dev desktops are deployed to machines with different architectures
(amd64 and arm64), which makes it necessary to discover the target
triple when linking the stages. The current solution was chosen based on
the following Stack Overflow post:

https://stackoverflow.com/questions/52996949/how-can-i-find-the-current-rust-compilers-default-llvm-target-triple

Author: jdno

ansible/roles/dev-desktop/files/scripts/link_rust.sh

@@ -5,18 +5,21 @@
 set -euo pipefail
 IFS=$'\n\t'
 
+# Discover target triple (e.g. "aarch64-unknown-linux-gnu")
+target="$(rustc -vV | awk '/host/ { print $2 }')"
+
 for D in rust*; do
   if [ -d "${D}" ]; then
     pushd "${D}"
 
     ./x.py build
 
-    if [[ -d "$D/build/aarch64-unknown-linux-gnu/stage1" ]]; then
-      rustup toolchain link "$D"_stage1 "$D/build/aarch64-unknown-linux-gnu/stage1"
+    if [[ -d "$D/build/$target/stage1" ]]; then
+      rustup toolchain link "$D"_stage1 "$D/build/$target/stage1"
     fi
 
-    if [[ -d "$D/build/aarch64-unknown-linux-gnu/stage2" ]]; then
-      rustup toolchain link "$D"_stage2 "$D/build/aarch64-unknown-linux-gnu/stage2"
+    if [[ -d "$D/build/$target/stage2" ]]; then
+      rustup toolchain link "$D"_stage2 "$D/build/$target/stage2"
     fi
 
     popd