LU-534 test: nfsread_orphan_file test

LU-534 test: nfsread_orphan_file test

Reproducer of bug17764.

In order to hit the assertion the lustre file has to be open twice
from lustre clients, and once from nfs mount.  Then unlink and close
opened lustre file and read the file opened on nfs.

Bugzilla: 17764
Author: Elena Gryanova <elena.gryaznova@oracle.com>
Signed-off-by: Elena Gryanova <elena.gryaznova@oracle.com>
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: I05d8f04a2bd7c64864e1b82a07ef26a170887714
Reviewed-on: http://review.whamcloud.com/1895
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>