glusterd : release cluster wide locks in op-sm during failures

glusterd op-sm infrastructure has some loophole in handing error cases in
locking/unlocking phases which ends up having stale locks restricting
further transactions to go through.

This patch still doesn't handle all possible unlocking error cases as the
framework neither has retry mechanism nor the lock timeout. For eg - if
unlocking fails in one of the peer, cluster wide lock is not released and
further transaction can not be made until and unless originator node/the node
where unlocking failed is restarted.

Following test cases were executed (with the help of gdb) after applying this
patch:

* RPC timesout in lock cbk
* Decoding of RPC response in lock cbk fails
* RPC response is received from unknown peer in lock cbk
* Setting peerinfo in dictionary fails while sending lock request for first peer
  in the list
* Setting peerinfo in dictionary fails while sending lock request for other
  peers
* Lock RPC could not be sent for peers

For all above test cases the success criteria is not to have any stale locks

Change-Id: Ia1550341c31005c7850ee1b2697161c9ca04b01a
BUG: 1154635
Signed-off-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-on: http://review.gluster.org/9012
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>