LU-3335 scrub: recover OST-objects from /lost+found

Originally, Lustre used the tool ll_recover_lost_found_objs to recover
orphans under /lost+found under offline mode. With OI scrub introduced
it can be done by initial OI scrub during the OST mount automatically.

Test-Parameters: testlist=sanity-scrub
Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ibf7e51cc0de10def47a117217b84c2afcd1209ca
Reviewed-on: http://review.whamcloud.com/6857
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>