Allow building wheels in %pyproject_buildrequires to support other build backends
    
    The hook is optional, see https://www.python.org/dev/peps/pep-0517/#prepare-metadata-for-build-wheel
    
    > If a build frontend needs this information and the method is not defined,
    > it should call build_wheel and look at the resulting metadata directly.
    
    This is not yet automatically detected because the feature is provisional.
    Use `%pyproject_buildrequires -w` to opt-in.
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=2076994