LU-7310 clio: sync write should update mtime

LU-7310 clio: sync write should update mtime

Sync write should update m/ctime promptly, otherwise, stale m/ctime
could be updated on the OST object by the sync write RPC.

Added sanityn test_39d to verify this.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I9c7e1d75f610a3104c163df9d68c33442d8fe3f4
Reviewed-on: http://review.whamcloud.com/21063
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>