LU-1157 ldlm: replace waiting flock lists by hashes

LU-1157 ldlm: replace waiting flock lists by hashes

replace per-export list by per-export hash to locate a lock with
blocking export & owner.

Change-Id: I9c4089579bbf126781e232ea7021317fd10223e9
Xyratex-Bug-ID: MRP-385
Reviewed-by: Andriy Skulysh <andriy_skulysh@xyratex.com>
Signed-off-by: Vitaly Fertman <vitaly_fertman@xyratex.com>
Reviewed-on: http://review.whamcloud.com/2240
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>