LU-857 security: Lustre client tolerates enforced SELinux.

LU-857 security: Lustre client tolerates enforced SELinux.

Fix a bug which prevents Lustre clients to access directoriess when
SELinux is enforced, on RHEL 6.
This patch does not add a real SELinux support for Lustre but ables
to activate it for all other local filesystems, without Lustre
misbehaving.

Signed-off-by: Aurelien Degremont <aurelien.degremont@cea.fr>
Change-Id: Ia6692c96a8439eb9239cb55ce32a1c54958241d1
Reviewed-on: http://review.whamcloud.com/1703
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Niu Yawei <niu@whamcloud.com>
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>