Description:
------------
ob_start memory leak when specify chunsize parameter

Reproduce code:
---------------
<?php
function callback($buffer)
{
        return $buffer;
}
var_dump(ob_start("callback", 2));
echo "Hi!abc";
?>


Expected result:
----------------
boolean(true)
Hi!abc

Actual result:
--------------
bool(true)
Hi!abc[Mon Mar 27 12:32:37 2006]  Script:  'ob_start_memory_leak.php'
/home/xlchen/php-5.1.2/main/output.c(458) :  Freeing 0x0847F8D4 (9 bytes), script=ob_start_memory_leak.php
[Mon Mar 27 12:32:37 2006]  Script:  'ob_start_memory_leak.php'
/home/xlchen/php-5.1.2/main/output.c(456) :  Freeing 0x0846D384 (16 bytes), script=ob_start_memory_leak.php
=== Total 2 memory leaks detected ===