fsck.gfs2: Fix infinite loop in pass1b caused by duplicates in hash table
    
    If directory leaf blocks appeared more than once in a directory hash
    table, the duplicate references would be flagged as a duplicate,
    but since the duplicates were all from the same directory dinode,
    pass1b would not realize it needed to stop. This patch changes the
    criteria for duplicate processing so that it stops when the references
    are down to a single dinode, not a single reference. This allows
    it to get beyond pass1b so that the problem can be fixed by the hash
    table checking code in pass2.
    
    rhbz#984085