Filter out unused compiler options in client code
Filter out unused compiler options in client code

Closes #804

mattgodbolt/compiler-explorer,dkm/gcc-explorer,mattgodbolt/gcc-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,dkm/gcc-explorer