Merge #73: ci: Use correct variable to designate C++ compiler

e051a7d ci: Install wine32 package for Windows tests (Hennadii Stepanov)
2d2c695 build: Drop unused `CC` variable (Hennadii Stepanov)
1810fcb ci: Use correct variable to designate C++ compiler (Hennadii Stepanov)

Pull request description:

  Setting the `CC` variable does not affect the choice of a C++ compiler. `CXX` does.

  On the master branch (c36f1f0), CI tasks, which are supposed to compile using a non-default compiler (e.g., clang), actually are configured to use the default compiler. For example, https://api.cirrus-ci.com/v1/task/5042259930906624/logs/test.log:
  ```
  + clang -v
  Debian clang version 11.0.1-2
  Target: x86_64-pc-linux-gnu
  ...
  Build Options:
    with benchmarks         = yes
    with tests              = yes
    enable clmul fields     = yes
    CXX                     = g++ -std=c++11
  ...
  ```

ACKs for top commit:
  sipa:
    utACK e051a7d

Tree-SHA512: 618c4071c105791437312283f7f06a4e4bec7029cae6b2cf385e7fe94a8e3c12441534be9f7ba22d1608b435efec4455c01e966981870541876ca94c7110f099

Author: sipa

.cirrus.yml

@@ -72,9 +72,9 @@ task:
     << : *ENV_MATRIX_SAN_VALGRIND
   matrix:
     - env:
-        CC: gcc
+        CXX: g++
     - env:
-        CC: clang
+        CXX: clang++ -gdwarf-4
   << : *MERGE_BASE
   test_script:
     - ./ci/cirrus.sh
@@ -92,9 +92,10 @@ task:
     << : *ENV_MATRIX_VALGRIND
   matrix:
     - env:
-        CC: i686-linux-gnu-gcc
+        CXX: i686-linux-gnu-g++
     - env:
-        CC: clang --target=i686-pc-linux-gnu -isystem /usr/i686-linux-gnu/include
+        CXX: clang++ --target=i686-linux-gnu -gdwarf-4
+        CXXFLAGS: -g -O2 -isystem /usr/i686-linux-gnu/include -isystem /usr/i686-linux-gnu/include/c++/10/i686-linux-gnu
   test_script:
     - ./ci/cirrus.sh
   << : *CAT_LOGS
@@ -110,9 +111,9 @@ task:
     << : *ENV_MATRIX_SAN
   matrix:
     - env:
-        CC: gcc-9
+        CXX: g++-9
     - env:
-        CC: clang
+        CXX: clang++
   brew_script:
     - brew update
     - brew install automake libtool gcc@9

ci/cirrus.sh

@@ -7,7 +7,7 @@ export LC_ALL=C
 
 env >> test_env.log
 
-$CC -v || true
+$CXX -v || true
 valgrind --version || true
 
 ./autogen.sh

ci/linux-debian.Dockerfile

@@ -8,10 +8,10 @@ RUN apt-get update
 RUN apt-get install --no-install-recommends --no-upgrade -y \
         git ca-certificates \
         make automake libtool pkg-config dpkg-dev valgrind qemu-user \
-        gcc g++ clang libc6-dbg \
+        gcc g++ clang libclang-rt-dev libc6-dbg \
         gcc-i686-linux-gnu g++-i686-linux-gnu libc6-dev-i386-cross libc6-dbg:i386 \
         g++-s390x-linux-gnu gcc-s390x-linux-gnu libc6-dev-s390x-cross libc6-dbg:s390x \
-        wine g++-mingw-w64-x86-64
+        wine wine32:i386 g++-mingw-w64-x86-64
 
 # Run a dummy command in wine to make it set up configuration
 RUN wine true || true

configure.ac

@@ -119,7 +119,6 @@ if test "x$use_ccache" != "xno"; then
     fi
   else
     use_ccache=yes
-    CC="$ac_cv_path_CCACHE $CC"
     CXX="$ac_cv_path_CCACHE $CXX"
   fi
   AC_MSG_RESULT($use_ccache)