Fix potentially crash in `%n` of `mrb_vformat()` with 64-bit `int`
If `mrb_sym` is smaller than `int`, it is promoted to `int`.
@@ -302,7 +302,11 @@ mrb_vformat(mrb_state *mrb, const char *format, va_list ap)
mrb_gc_arena_restore(mrb, ai);
break;
case 'n':
+#if UINT32_MAX < INT_MAX
+ obj = mrb_symbol_value((mrb_sym)va_arg(ap, int));
+#else
obj = mrb_symbol_value(va_arg(ap, mrb_sym));
+#endif
goto L_cat_obj;
case 's':
chars = va_arg(ap, char*);
