MB-8161: Traverse the whole future queue when a task is woken

If a task is woken up then the future queue might not be in order
so we need to check each job in the future queue to make sure we
find all of the jobs that are ready to run.

Change-Id: I8505ba86180672dbb5092407debbbf777288155e
Reviewed-on: http://review.couchbase.org/25925
Reviewed-by: Jin Lim <jin@couchbase.com>
Tested-by: Jin Lim <jin@couchbase.com>