Drop qt4 macros
    
    Suggested by Sandro Mani
    (https://src.fedoraproject.org/rpms/mingw-filesystem/pull-request/8)
    
    I think we could just drop qt4 (and kde4) everywhere. mingw-qt (aka Qt4)
    has been removed two years ago (and was FTBFS for another year or two
    before that).
    
    Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>