LU-8041 mdd: increasing only atime update on close

LU-8041 mdd: increasing only atime update on close

The atime update on close should be increasing only, otherwise,
the atime could be overwritten by stale client's atime.

This patch also changed client to clear out the ATTR_ATIME
flag fro close RPC when atime == 0, so that patch client won't
overwrite the unpatched server with 0 atime.

A test case sanity 39p is added to verify that close won't
overwrite atime with zero, and sanity 39l is adjusted as well.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I40d1103ddfea184d82170a6795f89ce303a5c14e
Reviewed-on: http://review.whamcloud.com/19932
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>