Description:
------------
When setting the serialize handler to wddx in php.in:
session.serialize_handler = wddx
using any Umlaut in a $_SESSION variable will lead to misbehaviour of the system e.g. Apache crashing or the session file content to be destroyed

Reproduce code:
---------------
sesstest1.php:
=============
<?php
    session_start();
    $_SESSION['sess_var'] = "?????????";
    session_write_close();
    echo "The content is ". $_SESSION['sess_var']. "<br />";
?>
<a href="sesstest2.php?<?php echo SID?>">Page 2 </a>
sesstest2.php:
=============
<?php
    session_start();
    echo "The content is ".$_SESSION['sess_var']."<br />";
    unset ($_SESSION['sess_var']);
    session_write_close();
?>
<a href="sesstest1.php?<?php echo SID?>">Page 1</a>

Expected result:
----------------
there are several ways to do this properly, one is to set the encoding:
<?xml version="1.0" encoding="ISO-8859-1"?>
in the first line of the wddx file, another one is to use utf-8 encoding on encoding and decoding

Actual result:
--------------
<wddxPacket version='1.0'><header/><data><struct><var name='sess_var'><string>?????????</string></var></struct></data></wddxPacket>

And the system might throw-up on decoding when e.g. using french, spanish, swedish or other accented characters.