github: Don't build with dylibs enabled in the msys2 mingw64 environment

The total number of exported symbols in this build configuration has
now reached the limit for the number of exported symbols in a DLL,
with the latest version of llvm-project from git.

This isn't an issue when building with Clang, as it marks many
symbols as excluded from auto-export.

.github/workflows/build.yml

@@ -254,7 +254,10 @@ jobs:
           SOURCE_DATE_EPOCH: ${{needs.prepare.outputs.COMMIT_DATE_UNIX}}
           BUILD_DATE: ${{needs.prepare.outputs.BUILD_DATE}}
         run: |
-          ./build-all.sh $(pwd)/install/llvm-mingw --disable-clang-tools-extra --disable-lldb
+          if [ "${{matrix.sys}}" = "mingw64" ]; then
+              ARGS="--disable-dylib"
+          fi
+          ./build-all.sh $(pwd)/install/llvm-mingw --disable-clang-tools-extra --disable-lldb $ARGS
           .github/workflows/store-version.sh install/llvm-mingw/versions.txt
           ./copy-msys-dependencies.sh $(pwd)/install/llvm-mingw ${{matrix.sys}}
           ./run-tests.sh $(pwd)/install/llvm-mingw