LU-1866 lfsck: FID-in-{dirent,LMA} check and repair

LU-1866 lfsck: FID-in-{dirent,LMA} check and repair

As part of LFSCK 1.5, it implementes the following functionalities:

1) Verify and rebuild FID-in-dirent, mainly for MDT file-level
   backup/restore.

2) (Partly) verify and rebuild FID-in-LMA: if the FID-in-dirent
   is valid but FID-in-LMA is missed, then the later one will be
   repaired; but if both are missed, then it is OI scrub's duty
   to repair the inconsistency.

3) (Partly) handle IGIF objects upgrading: build IGIF-in-dirent
   for IGIF objects. The other two parts work for IGIF objects
   upgrading are:

3.1) Generate IGIF-in-LMA, which has been done by OI scrub in
     former patch(es).

3.2) Generate linkEA, which will be done by up layer LFSCK in
     other patch(es).

Test-Parameters: envdefinitions=ENABLE_QUOTA=yes testlist=sanity-lfsck

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ibb317f0f3f3e9cf6db56bfa25f55d2017b0e1937
Reviewed-on: http://review.whamcloud.com/4912
Tested-by: Hudson
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>