cluster/dht: Ignore subvols with error in min-free-disk/inodes

Currently when selecting a alternative subvolume when hashed
subvol has exceeded min-free-disk/inodes, we do not check if
layouts have errors (including decommissioning). This leads
to data being written to those subvolumes, and in case of
decommissioning, will lead to data loss.

BUG: 982919

> Original-Author: shishir gowda <sgowda@redhat.com>
> Reviewed-on: http://review.gluster.org/5299

Change-Id: If301a86cf3ca5fad6529bd2e61382f9901663ba0
Signed-off-by: Amar Tumballi <amarts@redhat.com>
Reviewed-on: http://review.gluster.org/5888
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>