testsuite: put contents of regression.diffs to stdout
    
    .. to help users who face issues like rhbz#1118392.
    
    Also, testsuite consists of several 'make check' runs.  From now,
    continue with checking if some of 'make check' runs failed;  just
    to be sure we have complete test results.  Make the test failed
    once all testing is done.
    
    Resolves: #1118392
    Version: 9.3.5-8