Sending pollable signals is most likely done from a context which
cannot immediately reschedule, but will certainly do so later on
(e.g. IRQ handler). There is no point in triggering a reschedule in
this overwhelmingly frequent case.

Rare callers which might want to reschedule immediately after the
events are posted must do so by calling evl_schedule() explicitly
(none in tree yet).

Signed-off-by: Philippe Gerum <rpm@xenomai.org>