cluster/afr: Make entry-self-heal in afr-v2 compatible with afr-v1

Problem:
entry self-heal in 3.6 and above, takes full lock on the directory only for the
duration of figuring out the xattrs of the directories where as 3.5 takes locks
through out the entry-self-heal. If the cluster is heterogeneous then there is
a chance that 3.6 self-heal is triggered and then 3.5 self-heal will also
triggered and both the self-heal daemons of 3.5 and 3.6 do self-heal.

Fix:
In 3.6.x and above get an entry lock on a very long name before entry self-heal
begins so that 3.5 entry self-heal will not get locks until 3.6.x entry
self-heal completes.

Change-Id: I71b6958dfe33056ed0a5a237e64e8506c3b0fccc
BUG: 1168189
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/9227
Reviewed-by: Krutika Dhananjay <kdhananj@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>