gfs2_edit: Add statfs fields to log header descriptions
    
    Changes the output of 'gfs2_edit -p journal0 $dev' from:
    
      0x24 (j+   0): Log header: Seq: 0x1dd6, tail: 0x0, blk: 0x0 [UNMOUNT/USERSPACE]
    
    to:
    
      0x24 (j+   0): Log header: seq: 0x1dd6, tail: 0x0, blk: 0x0, tot: 0x0, fr: 0x0, di: 0x0 [UNMOUNT/USERSPACE]
    
    Signed-off-by: Andrew Price <anprice@redhat.com>