Try llvm-cov on CI

Author: pcolby

.github/workflows/build.yaml

@@ -29,15 +29,15 @@ jobs:
           - 6.7.3
           - 6.8.0
         env:
-          - { cc: clang, cxx: clang++, coverage: false }
-          - { cc: gcc, cxx: g++, coverage: false }
+          - { cc: clang, cxx: clang++, coverage: true }
+          #- { cc: gcc, cxx: g++, coverage: false }
           - { cc: gcc, cxx: g++, coverage: true }
     steps:
       - name: Upgrade OS
         run: |
           sudo apt-mark hold grub-efi-amd64-signed
           sudo apt update && sudo apt upgrade
-          sudo apt install lcov libfuse2
+          sudo apt install lcov libfuse2 llvm
       - uses: actions/setup-python@v5
         with:
           python-version: '>=3.9'
@@ -166,8 +166,8 @@ jobs:
           - 6.8.0
         os: [ 'macos-13', 'macos-14', 'macos-15' ]
         env:
-          - { cc: clang, cxx: clang++, coverage: false }
-          - { cc: gcc-14, cxx: g++-14, coverage: false }
+          - { cc: clang, cxx: clang++, coverage: true }
+          #- { cc: gcc-14, cxx: g++-14, coverage: false }
           - { cc: gcc-14, cxx: g++-14, coverage: true }
         exclude:
           # GitHub's macOS 14+ gcc can only target arm64, but Qt didn't add Apple arm64 support until Qt 6.2, so:
@@ -309,6 +309,7 @@ jobs:
           if-no-files-found: error
 
   win:
+    if: false
     runs-on: windows-latest
     defaults: { run: { shell: cmd } }
     strategy: