configs: Always exit with code 0

Update simulation.py to always exit with code 0 assuming the simulation
exits normally. If the running application has a return code that is non
zero, then print the return code before exiting.

Change-Id: I1983985d50311627574d4364b32ee961ae88e003
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-on: https://gem5-review.googlesource.com/4880

configs/common/Simulation.py

@@ -716,5 +716,5 @@ def run(options, root, testsys, cpu_class):
     if options.checkpoint_at_end:
         m5.checkpoint(joinpath(cptdir, "cpt.%d"))
 
-    if not m5.options.interactive:
-        sys.exit(exit_event.getCode())
+    if exit_event.getCode() != 0:
+        print("Simulated exit code not 0! Exit code is", exit_event.getCode())