skip when mbstring missing (no warning)

Author: remicollet

ext/standard/tests/strings/htmlentities25.phpt

@@ -4,6 +4,10 @@ htmlentities() should not be influenced by mb_internal_encoding()
 default_charset=
 internal_encoding=
 mbstring.internal_encoding=ISO-8859-1
+--SKIPIF--
+<?php
+	extension_loaded("mbstring") or die("skip mbstring not available\n");
+?>
 --FILE--
 <?php