message: Enable all warnings on builds.
  Also switch off the progress outputs by cmake, they are
  annoying and hide messages in-between.
diff: @@ -69,6 +69,8 @@ jobs:
  echo 'CXX=g++-7' >> $GITHUB_ENV
  echo 'PATH=/usr/lib/ccache:'"$PATH" >> $GITHUB_ENV
  echo 'PREFIX=/tmp/surelog-install' >> $GITHUB_ENV
  + echo "ADDITIONAL_CMAKE_OPTIONS='-DMY_CXX_WARNING_FLAGS="-W -Wall -Wextra -Wno-unused-parameter -Wno-unused-variable -Werror -UNDEBUG"'" >> $GITHUB_ENV
  + echo 'RULE_MESSAGES=off' >> $GITHUB_ENV
  - name: Show shell configuration
  run: |
  @@ -461,6 +463,7 @@ jobs:
  - name: Configure shell
  run: |
  echo 'PATH=/usr/lib/ccache:'"$PATH" >> $GITHUB_ENV
  + echo 'RULE_MESSAGES=off' >> $GITHUB_ENV
  - name: Prepare source
  run: |
  