cluster/afr: Fixed mem leaks in self-heal code path.

AFR_STACK_RESET previously didn't cleanup afr_local_t,
leading to memory leaks. With this patch, cleanup is
done.

All credit goes to Pranith Kumar Karampuri.

Change-Id: I3c727ff4bb323dccb81da4b3168ac69bb340d17d
BUG: 1145471
Signed-off-by: Anuradha <atalur@redhat.com>
Reviewed-on: http://review.gluster.org/8821
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com>