Disable rgb10 configs by default
    
    rgb10 configs are not handled very well by applications using clutter,
    and possibly other applications as well, so don't break those by
    disabling support for rgb10 configs by default.
    
    Also re-add python2 as a build requirement, as merge_driinfo.py
    depends on it.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1560481