FollyExecutorPool does not update wakeTime when wake() called

If a task managed by an ExecutorPool is scheduled to run immediately via wake(), it's wakeTime - the time it was desired to run - should be reset to "now" - given that's the new time for it to run. Waketime is then used to calculate the queue time of the task - how long the task has been waiting to run, which is exposed via cbstats scheduler.

However the FollyExecutorPool implementation fails to update the waketime when wake() is called; leaving at its previous value. This can give inaccurate values for queue time, as the the queue time is reported as zero (capped from a large negative value: now() - waketime.