Update mb_output_handler_pass.phpt

Also got a note in the GitHub interface: `We’ve detected the file encoding as ISO-8859-1. When you commit changes we will transcode it to UTF-8.`

Author: DanielEScherzer

ext/mbstring/tests/mb_output_handler_pass.phpt

@@ -20,8 +20,10 @@ ob_start('mb_output_handler');
 mb_http_output("pass");
 var_dump("\xff");
 ?>
---EXPECT--
+--EXPECTF--
 string(4) "pass"
-string(1) "ÿ"
+string(1) "ÿ"
+
+Deprecated: ob_end_flush(): Producing output from user output handler mb_output_handler is deprecated in %s on line %d
 string(1) "?"
-string(1) "ÿ"
+string(1) "ÿ"