address rpmdeps test suggestions
    
    Subpackage mutter-tests carries 'Requires: libmutter-test-12.so'
    which comes from subpackage mutter-devel but does not carry an
    explicit package version requirement.
    
    Added 'Requires: mutter-devel = %{version}-%{release}' to the spec
    file to avoid the need to test interoperability between various
    combinations of old and new subpackages.
    
    Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>