small changes to memory stuffs to hopefully not fail

kern/synchprobs/traffic_synch.c

@@ -132,7 +132,7 @@ static void dellist(list * dead)
   while (temp)
   {
     car * temp2 = temp->next;
-    cv_destroy(temp->cv);
+    if (temp->cv) cv_destroy(temp->cv);
     kfree(temp);
     temp = temp2;
   }