gfs2_convert: gfs2_convert doesn't resume after interrupted conversion
    
    This patch causes the inode conversion routine to skip over the jindex and
    rindex inodes. Without this patch, the jindex and rindex inodes are converted
    to gfs2 format and once converted, there's no way to go back to gfs1 for these
    two inodes were the convert to be interrupted somehow. In the eyes of the
    subsequent gfs2_convert run, these two inodes would be corrupt and gfs2_convert
    would bail out of the conversion.
    Skipping conversion of these two inodes doesn't affect gfs2_convert as these
    two inodes are freed from disk towards the end of the conversion process. New
    jindex and rindex inodes are created for gfs2 separately in the master
    directory.
    
    Note: This issue with reconversion failing occurs only when the jindex/rindex
    inodes are unstuffed. When stuffed, gfs1 and gfs2 inodes have a similar
    structure, so it doesn't matter if these inodes are converted or not, however
    with inode height > 0 the structures of gfs1 and gfs2 differ.
    
    Resolves: rhbz#636157
    Signed-off-by: Abhi Das <adas@redhat.com>