systemc: Make sure an immediate notification overrides a delayed one.

If an event has a delayed notification pending, that should be cleared
if it's later notified immediately.

Change-Id: I4272f6b47a41d80756769f3fe69069a00016dbd6
Reviewed-on: https://gem5-review.googlesource.com/12223
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/event.cc

@@ -122,6 +122,10 @@ Event::getParentObject() const
 void
 Event::notify()
 {
+    // An immediate notification overrides any pending delayed notification.
+    if (delayedNotify.scheduled())
+        scheduler.deschedule(&delayedNotify);
+
     auto local_sensitivities = sensitivities;
     for (auto s: local_sensitivities)
         s->notify(this);