eventq: convert all usage of events to use the new API.

For now, there is still a single global event queue, but this is
necessary for making the steps towards a parallelized m5.

src/python/m5/main.py

@@ -326,7 +326,9 @@ def main():
     if options.trace_start:
         def enable_trace():
             internal.trace.cvar.enabled = True
-        event.create(enable_trace, int(options.trace_start))
+        
+        e = event.create(enable_trace)
+        event.mainq.schedule(e, options.trace_start)
     else:
         internal.trace.cvar.enabled = True