Add OBD_CONNECT2_GETATTR_PFID connect flag to pack parent FID in
getattr request, which will be used to check whether target is
remote object, if so, don't take LOOKUP lock, otherwise client
may see stale directory entries.

Test-parameters: trivial

Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: Ibdf880934456f255f83cd4bac9d61ab5e1ed7330
Reviewed-on: https://review.whamcloud.com/39289


Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>