cluster/afr: For entry self heal, mark all source bricks

Problem:
Whenever a new brick is added into a replicate volume, all
source bricks are not marked as source. Only one of them is
marked as source. Here marked as source refers to adding
extended attribute at the backend of a file corresponding to
the newly added brick. As well as source bricks should point
to the newly added brick so that heal can be triggered.

Fix:
All source bricks will now point to newly added bricks and heal
can be triggered based on the extended attributes.

Change-Id: Ia7cf118270fecc429bdecddbcb9201f23fedc7a1
BUG: 1037501
Signed-off-by: Venkatesh Somyajulu <vsomyaju@redhat.com>
Reviewed-on: http://review.gluster.org/6419
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>