gcc-problem-matcher with build dir support

This is just gcc-problem-matcher but it ignores ../ at the start of the build dir

Github Action to problem match output from gcc. This allows warnings and errors from the compiler to be prominently featured in pull requests like so:

This is a direct port of the $gcc rule from vscode-cpptools. Typical usage will be:

    - uses: Joshua-Ashton/gcc-problem-matcher@master
    - name: Build Project
      run: make

Note that this action does not build your code for you. It only makes the errors and warnings from your compiler more prominent.

Development

Keep this up-to-date with the upstream vscode-cpptools gcc matcher: https://github.com/microsoft/vscode-cpptools/blob/a8285cbc0efb5b09c2d2229b0e0772dcb3b602df/Extension/package.json#L76-L94