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.

Change-Id: Ie0c6cf4a29d7c53d8a6d8a8c1bd595cf58a0012a
BUG: 982919
Signed-off-by: shishir gowda <sgowda@redhat.com>
Reviewed-on: http://review.gluster.org/5299
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>