this is meant as a hint that there can be no event at the moment
and in this special case iscsi_service will return immediately.
We use this at the moment in the case of a wait for a reconnect
in which case we would enter a busy loop waiting for that
reconnect. The 0 means do not poll for the client application.
Do not poll, just wait a little (a few hundred ms) and call iscsi_which_events
again. The wait should be timer driven or at least non busy looping,
of course.
Signed-off-by: Peter Lieven <pl@kamp.de>