* src/threads/lock.cpp (sable_flc_waiting, notify_flc_waiters): Use a simpler

* src/threads/lock.cpp (sable_flc_waiting, notify_flc_waiters): Use a simpler
mechanism for unblocking threads on the FLC list; added comments.

I've had this one sitting in my queue for a long time but didn't want to
commit because this would have required a change in the description of this
algorithm in my thesis, and it would have obsoleted the cool drawing I've made
of the whole progress ;). But now that I've been freed from such worries, here
it goes...

--HG--
extra : transplant_source : t%940%5D%FE%98%87%BF%B1%E3%3F%A8QzH%27%93P%22%7F