LU-4389 clio: update file attributes after sync

LU-4389 clio: update file attributes after sync

This really only affects ZFS, because zfs does not update # of blocks
until the blocks are flushed to disk.

This patch update file's blocks attribute after OST_SYNC completes.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: I2b62dff5acda2984f60d5ed5df4ad19144cd6829
Reviewed-on: http://review.whamcloud.com/12915
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>