add small delay before triggering events for ib_wait_event

we want to make sure ib_wait_event was called before
the events are posted. sleeping doesn't really guarantee
that, but helps if the system is not overloaded
skip ib_wait_event tests under AUTOMATED_TESTING

there's no guarantee that the ib_wait_event call will
happen before the worker thread starts posting events

the delay introduced in eca0f35 helps, but there's no
amount of delay that would guarantee proper order of
scheduling under high load

See http://bugs.debian.org/719582