glusterd/snapshot : Clean up of old barrier code.

As a new barrier translator is introduced, we dont require
the old barrier code. Hence cleaning thar up.

Change-Id: Ieedca6f33a746898f0d2332fda1f1d4c86fff98f
BUG: 1061685
Signed-off-by: Sachin Pandit <spandit@redhat.com>
Reviewed-on: http://review.gluster.org/7577
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>
Reviewed-by: Vijaikumar Mallikarjuna <vmallika@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>