Fix Windows CI: Add pkg-config and set PKG_CONFIG_PATH for conda

Windows conda uses a different directory structure than Linux:
- Linux: $CONDA_PREFIX/lib/pkgconfig
- Windows: $CONDA_PREFIX/Library/lib/pkgconfig

Also install pkg-config from conda to avoid conflicts with Strawberry Perl's pkg-config.BAT

Author: ilayn

.github/workflows/test-matrix.yml

@@ -38,7 +38,7 @@ jobs:
       if: runner.os == 'Windows'
       shell: bash -l {0}
       run: |
-        conda install -y meson ninja numpy pytest openblas clang llvm-tools lld
+        conda install -y meson ninja numpy pytest openblas clang llvm-tools lld pkg-config
 
     - name: Build SLICUTLET (Linux/macOS)
       if: runner.os != 'Windows'
@@ -56,6 +56,8 @@ jobs:
         # Force clang to target MinGW-w64 instead of MSVC for C11 complex support
         export CC="clang --target=x86_64-w64-mingw32"
         export CXX="clang++ --target=x86_64-w64-mingw32"
+        # Windows conda uses Library/lib/pkgconfig not lib/pkgconfig
+        export PKG_CONFIG_PATH="$CONDA_PREFIX/Library/lib/pkgconfig:$PKG_CONFIG_PATH"
         meson setup build -Dpython=true
         meson install -C build --destdir="${PWD}/build-install"
 

.github/workflows/test-windows.yml

@@ -28,14 +28,17 @@ jobs:
           openblas \
           clang \
           llvm-tools \
-          lld
+          lld \
+          pkg-config
 
     - name: Build SLICUTLET (using LLVM/clang with MinGW target)
       shell: bash -l {0}
       run: |
         # Force clang to target MinGW-w64 instead of MSVC for C11 complex support
         export CC="clang --target=x86_64-w64-mingw32"
         export CXX="clang++ --target=x86_64-w64-mingw32"
+        # Ensure pkg-config can find conda packages
+        export PKG_CONFIG_PATH="$CONDA_PREFIX/Library/lib/pkgconfig:$PKG_CONFIG_PATH"
         meson setup build -Dpython=true
         meson install -C build --destdir="${PWD}/build-install"