Fix bug in stack creation which would count one extra argument for argc

src/userprog/process.c

@@ -102,7 +102,7 @@ start_process (void *file_name_)
   struct list arg_list;
   list_init (&arg_list);
 
-  int arg_count = 1;
+  int arg_count = 0;
   while (arg != NULL)
     {
       push_to_stack (&if_.esp, arg, (strlen (arg) + 1) * sizeof (char));