dht: Enable mem-accounting for nufa

Change-Id: I0cf8a59c81e30603aadc45393bbd49d80ae1621f
BUG: 912657
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/4542
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>