systemc: Run delta notifications in reverse insertion order.

This is sort of pointless, except that it matches Accellera's behavior.

Change-Id: Ia63f2de998157aa68ce36fdc2ba39ca7a80fecbe
Reviewed-on: https://gem5-review.googlesource.com/c/13295
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/scheduler.cc

@@ -330,7 +330,7 @@ Scheduler::runDelta()
 
     try {
         while (!deltas.empty())
-            deltas.front()->run();
+            deltas.back()->run();
     } catch (...) {
         throwToScMain();
     }