Do not run the first time step if the compilation failed.

This patch fixes another minor problem introduced by the process
end of simulation events. Specifically if the compilation has
indicated we should not run do not even start the main event loop.

vvp/schedule.cc

@@ -618,7 +618,7 @@ void schedule_simulate(void)
 
       signals_capture();
 
-      while (sched_list) {
+      if (schedule_runnable) while (sched_list) {
 
 	    if (schedule_stopped_flag) {
 		  schedule_stopped_flag = false;