cluster/dht: Fix non-regular file ownership during rebalance

Currently non-regular files were created as root:root, and
their ownership never healed during rebalance process.

Also, in dht_linkfile_attr_heal, we have to heal the linkfiles
as default, as currently linkfiles are created as root:root.

That check existed, as earlier linkfiles were created as
frame->root->uid/gid

Change-Id: I6cd88361b81bdd500e15bc47b623f5db8eec88e9
BUG: 990154
Signed-off-by: shishir gowda <sgowda@redhat.com>
Reviewed-on: http://review.gluster.org/5434
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>