Description:
------------
xml_set_object causes memory leak....

in example, an infinite loop i written which should not constantly increase memory...

When xml_set_object($this->parser, &$this); is removed, memory leak stops...

Reproduce code:
---------------
class xml
	{
	function __construct()
		{
		$this->parser = xml_parser_create();
		xml_set_object($this->parser, &$this);
		}
	
	function __destruct()
		{
		xml_parser_free($this->parser);
		}
	}

while (true)
	{
	usleep(1000);
	$x = new xml();
	unset($x);
	}

Expected result:
----------------
Nothing should happen ....

Actual result:
--------------
when below code is run.. memory usage increases 5 MB/s for abount 15 seconds and then:

PHP Fatal error:  Allowed memory size of 16777216 bytes exhausted (tried to allocate 16 bytes) in D:\source\php\include\xml.php on line 18
Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate
16 bytes) in D:\source\php\include\xml.php on line 18