LU-3928 ost: update OST export connection flags

LU-3928 ost: update OST export connection flags

LU-1623 introduce atomically update export connection flags for MDT.
The same issue exist for OST. In any case the flags would be updated
for export, even if error handling code path occured.

Signed-off-by: Alexander Boyko <alexander_boyko@xyratex.com>
Xyratex-bug-id: MRP-1306
Change-Id: I4f93ff88cd94467cfe6d6fdb9d7214c727c43db2
Reviewed-on: http://review.whamcloud.com/7611
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>