Add grep patterns for checking skipped tests
    
    It is useful to check the output of the test suite for skipped tests.
    This reveals tests which may have missing BuildRequires or other issues.
    Doing so can be tedious due to the many legitimate tests we skip.  Keep
    a list of patterns matching tests we skip intentionally.
    
    To use this list to process a build.log, run something like the
    following:
    
        $ egrep '# SKIP|skipped:' build.log | egrep -v -f git.skip-test-patterns
    
    There should be no output.  Any output should be checked and the tests
    fixed or added to the skip patterns file.