LU-4805 lmv: lookup remote migrating object in LMV

If remote object is being found in a migrating directory,
it should continue to lookup the object in remote MDT,
instead of return.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ib3309e255e2e1fe5789854f47e470f3085d6f6e6
Reviewed-on: http://review.whamcloud.com/9806
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>