MRP-1641 lprocfs: mdt/*/exports/*/uuid is empty after remount

need to assign exp_nid_stats even if old stats are present
The issue was introduced by
commit 79683154758ed5e71aa755cdf4c385bc621fb966

Change-Id: Ib8660705037e1b97f5eb6a74b5c09e7cd71c3953
Signed-off-by: Andriy Skulysh <Andriy_Skulysh@xyratex.com>
Reviewed-on: http://es-gerrit.xyus.xyratex.com:8080/1496
Tested-by: Jenkins
Reviewed-by: Cheng Shao <cheng_shao@xyratex.com>
Reviewed-by: Alexey Lyashkov <alexey_lyashkov@xyratex.com>
Tested-by: Elena Gryaznova <elena_gryaznova@xyratex.com>
Reviewed-by: Vitaly Fertman <vitaly_fertman@xyratex.com>
LU-748 test: shorten the runtime of sanity subtest_220

in sanity.sh, test_220 tries to exhaust all of the inodes on the OSTs
in order to verify that when it returns -ENOSPC to inode precreate
request, but there is still free blocks, then the MDS continues to use
these precreated inodes on the OSTs.

Signed-off-by: Hongchao Zhang <hongchao.zhang@whamcloud.com>
Change-Id: Icaad07311125f362f0efb26da76534c7dca27b6a
Reviewed-on: http://review.whamcloud.com/1676
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>