ci: don't build the C library with MinGW

Only the C compiler is currently installed, without its binutils.

.github/workflows/build.yml

@@ -163,14 +163,6 @@ jobs:
       env:
         CFLAGS: -g -Werror -Wall -Wextra -Wshadow -Wpedantic -Werror=incompatible-pointer-types
 
-    - name: Build C library on Windows (make)
-      if: ${{ runner.os == 'Windows' }}
-      run: make.sh -j CC="$CC" CFLAGS="$CFLAGS" AR="$AR"
-      env:
-        CC: x86_64-w64-mingw32-gcc
-        AR: x86_64-w64-mingw32-ar
-        CFLAGS: -g -Werror -Wall -Wextra -Wshadow -Wpedantic -Werror=incompatible-pointer-types
-
     - name: Build C library (CMake)
       if: ${{ !matrix.use-cross }}
       run: |