Add missing SKIPIF (mbstring)

Author: Fabien Villepinte

ext/mbstring/tests/bug77165.phpt

@@ -1,5 +1,7 @@
 --TEST--
 Bug #77165: mb_check_encoding crashes when argument given an empty array
+--SKIPIF--
+<?php require 'skipif.inc'; ?>
 --FILE--
 <?php
 var_dump(mb_check_encoding(array()));

ext/mbstring/tests/bug77454.phpt

@@ -1,5 +1,7 @@
 --TEST--
 Bug #77454: mb_scrub() silently truncates after a null byte
+--SKIPIF--
+<?php require 'skipif.inc'; ?>
 --FILE--
 <?php
 $str = "before\0after";

ext/mbstring/tests/internal_encoding.phpt

@@ -1,5 +1,7 @@
 --TEST--
 Check that "internal_encoding" ini is picked up by mbstring
+--SKIPIF--
+<?php require 'skipif.inc'; ?>
 --INI--
 internal_encoding=iso-8859-1
 --FILE--

ext/mbstring/tests/mb_convert_encoding_leak.phpt

@@ -1,5 +1,7 @@
 --TEST--
 mb_convert_encoding() shouldn't leak keys
+--SKIPIF--
+<?php require 'skipif.inc'; ?>
 --FILE--
 <?php