LU-56 ldlm: SMP improvement for ldlm_lock_cancel

LU-56 ldlm: SMP improvement for ldlm_lock_cancel

ldlm_del_waiting_lock() is always called twice in ldlm_lock_cancel
even the ldlm_lock is not on expiring waiter list, this is bad for
performance because it needs to grab a global lock and disable
softirq.
This patch add a new bit l_waited to ldlm_lock, it's set only if
ldlm_add_waiting_lock() is ever called, and we can bypass
ldlm_del_waiting_lock() in ldlm_lock_cancel() if w/o this bit.

I also adopted patch(32562) on BZ 20509 because it's necessary for
this improvement.

Signed-off-by: Liang Zhen <liang@whamcloud.com>
Change-Id: Ie48d527b8da187a88646aa070be3aa4beb304b1d
Reviewed-on: http://review.whamcloud.com/3141
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>