LU-957 scrub: OI scrub against ldiskfs

LU-957 scrub: OI scrub against ldiskfs

The OI scrub is totally implemented inside osd-ldiskfs,
and driven by the inode iterator. For each object with
normal fid, its fid in the LMA and related OI entry in
the OI file will be compared, if they are inconsistent,
then the OI entry will be updated.

Signed-off-by: Fan Yong <yong.fan@whamcloud.com>
Change-Id: I04d25b3433336fb63c312f795a8631328beb3aa7
Reviewed-on: http://review.whamcloud.com/2552
Tested-by: Hudson
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>