LU-2858 mdt: check .lustre before reint operation.

1. Check .lustre in MDT layer to make sure any attempt to change
.lustre will return EPERMT.

2. send parent fid for remote open, so mdt can check whether it
will create lov object for the fid under OBF.

3. add a few test cases in sanity 154(OBF checking) to check .lustre
and remote fid

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Ia708856e026a959ca30b06fdd3acd907e5d1b913
Reviewed-on: http://review.whamcloud.com/5555
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John Hammond <johnlockwoodhammond@gmail.com>