GitHub-CI (macos): Use pkg-config files for Qt6 at default location.

* .github/workflows/stable/make-macos.yaml: Homebrew updated Qt6 to version
6.9.0 or newer which installs the pkg-config files at the default location.
Simplify build rules accordingly.

Author: mmuetzel

.github/workflows/make-macos.yaml

@@ -33,17 +33,13 @@ jobs:
           - compiler: clang
             cc: "clang"
             cxx: "clang++"
-            # Qt6 doesn't install pkg-config files on macOS by default. See: https://bugreports.qt.io/browse/QTBUG-86080
-            # Homebrew installs "unofficial" .pc files for it in a non-default location.
-            qt-pkg-config-path: opt/qt@6/libexec/lib/pkgconfig
           - os: macos-13
             qt: "5"
             cc: "clang"
             cxx: "clang++"
             # SUNDIALS >= 6.5.0 doesn't compile with the default flags determined
             # by the configure script. Set CXX manually to enable building with it.
             cxx-compiler-flags: "-std=gnu++14"
-            qt-pkg-config-path: opt/qt@5/lib/pkgconfig
 
     env:
       CC: ${{ matrix.cc }}
@@ -157,7 +153,7 @@ jobs:
             CPPFLAGS="-I${HOMEBREW_PREFIX}/opt/gettext/include -I${HOMEBREW_PREFIX}/opt/icu4c/include -I${HOMEBREW_PREFIX}/opt/libiconv/include -I${HOMEBREW_PREFIX}/opt/qt@${{ matrix.qt }}/include -I${HOMEBREW_PREFIX}/opt/readline/include -I${HOMEBREW_PREFIX}/opt/sqlite/include $MY_CPPFLAGS -I${HOMEBREW_PREFIX}/include" \
             CXXFLAGS="-O2 -g" \
             LDFLAGS="-L${HOMEBREW_PREFIX}/opt/bison/lib -L${HOMEBREW_PREFIX}/opt/gettext/lib -L${HOMEBREW_PREFIX}/opt/icu4c/lib -L${HOMEBREW_PREFIX}/opt/libiconv/lib -L${HOMEBREW_PREFIX}/opt/readline/lib -L${HOMEBREW_PREFIX}/opt/sqlite/lib $MY_LDFLAGS -L${HOMEBREW_PREFIX}/lib" \
-            PKG_CONFIG_PATH="${HOMEBREW_PREFIX}/opt/openblas/lib/pkgconfig:${HOMEBREW_PREFIX}/opt/icu4c/lib/pkgconfig:${HOMEBREW_PREFIX}/${{ matrix.qt-pkg-config-path }}" \
+            PKG_CONFIG_PATH="${HOMEBREW_PREFIX}/opt/openblas/lib/pkgconfig:${HOMEBREW_PREFIX}/opt/icu4c/lib/pkgconfig:${HOMEBREW_PREFIX}/opt/qt@${{ matrix.qt }}/lib/pkgconfig" \
             --with-qt=${{ matrix.qt }} \
             QCOLLECTIONGENERATOR="qhelpgenerator" \
             --with-x=no \