LU-5560 obd: reserve connection flag OBD_CONNECT2_FILE_SECCTX

LU-5560 obd: reserve connection flag OBD_CONNECT2_FILE_SECCTX

The connection flag OBD_CONNECT2_FILE_SECCTX will be set (in
ocd_connect_flags2) if an MDT supports setting the file security
context at create time.

This patch is ported from the following one:
Lustre-commit: f0f79ede2105dd40665bd8b60c2c5f274290ab57
Lustre-change: http://review.whamcloud.com/18420

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Intel-bug-id: LDEV-236
Change-Id: Ib79ef50bbcd68baa624ece109fa204dfd7f8b128
Reviewed-on: http://review.whamcloud.com/19970
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>