131b0092c6
A shutdown event specification is no longer part of the isc_task_create() API. Multiple shutdown events can be requested with isc_task_onshutdown(). Shutdown events are posted LIFO. The ability to send events can be enabled and disabled with isc_task_allowsend(). Event actions return void; the only way to shutdown a task is to call isc_task_shutdown(). There are no implicit event discards anymore. (There is no need for them, since event actions cannot request immediate shutdown anymore.)