MINOR: event_hdl: add event_hdl_async_equeue_isempty() function

Add event_hdl_async_equeue_isempty() to check is the event queue is
empty from an advanced async task handler.

If 68e692da0 ("MINOR: event_hdl: add event handler base api")
is being backported, then this commit should be backported with it.
1 file changed