message: Fix coverage build to include CXX define
  Also it seems like we don't need to restrict coverage build to
  Linux/clang?
diff: @@ -26,8 +26,8 @@ jobs:
  make test cxxstd=c++98 defines=${{matrix.defines}} config=debug -j2
  make test defines=${{matrix.defines}} config=sanitize -j2
  - name: make coverage
  - if: ${{matrix.os == 'ubuntu' && matrix.compiler == 'clang++'}}
  run: |
  + export CXX=${{matrix.compiler}}
  make test defines=${{matrix.defines}} config=coverage -j2
  bash <(curl -s https://codecov.io/bash) -f pugixml.cpp.gcov -X search -t ${{secrets.CODECOV_TOKEN}} -B ${{github.ref}}
  