fsck.gfs2: Undo partially done metadata records
    
    This patch fixes a problem with duplicate block processing where
    one reference is as metadata and another is not (reference as data
    or ea or something). The problem is that the metadata block may have
    been processed as metadata (for example, an indirect block pointing
    to a bunch of data blocks, so all blocks it references are now
    marked as metadata) but the last resolved duplicate is not as
    metadata, so the sub-blocks are never reprocessed, or "undone".
    This patch makes it so that basically if the first reference is
    as metadata (so we know we processed its sub-blocks) and the inode
    referencing it as metadata is the LAST inode to reference it as
    metadata, the sub-blocks are sent through "undo" processing.
    
    Signed-off-by: Bob Peterson <rpeterso@redhat.com>