Description:
------------
When track_errors is On then simple code causes php segfault.

It was tested with 5.3.6 final and also with recent php5.3-201104201030 snap.

Test script:
---------------
[arekm@t400 ~/public_html]$ cat a.ini
[PHP]
track_errors = On
[arekm@t400 ~/public_html]$ cat a.php
<?php
function testing($source) {
                unset($source[$cos]);
}
testing($_GET);
?>

[arekm@t400 ~/public_html]$ php -n -c a.ini a.php

zsh: segmentation fault  php -n -c a.ini a.php

Expected result:
----------------
No segfault.

Actual result:
--------------
Starting program: /usr/bin/php -n -c php.ini a.php
[Thread debugging using libthread_db enabled]

Program received signal SIGSEGV, Segmentation fault.
zval_mark_grey (pz=<value optimized out>) at /usr/src/debug/php-5.3.6.1/Zend/zend_gc.c:372
372                             pz = *(zval**)p->pData;
(gdb) bt
#0  zval_mark_grey (pz=<value optimized out>) at /usr/src/debug/php-5.3.6.1/Zend/zend_gc.c:372
#1  0x00007ffff7cb7c35 in gc_mark_roots () at /usr/src/debug/php-5.3.6.1/Zend/zend_gc.c:435
#2  gc_collect_cycles () at /usr/src/debug/php-5.3.6.1/Zend/zend_gc.c:664
#3  0x00007ffff7c9b0ed in zend_deactivate () at /usr/src/debug/php-5.3.6.1/Zend/zend.c:900
#4  0x00007ffff7c48a20 in php_request_shutdown (dummy=<value optimized out>) at /usr/src/debug/php-5.3.6.1/main/main.c:1637
#5  0x0000000000403d0c in main (argc=5, argv=0x7fffffffeb68) at /usr/src/debug/php-5.3.6.1/sapi/cli/php_cli.c:1374
(gdb) print p
$1 = (Bucket *) 0x400000000
(gdb) print p->pData
Cannot access memory at address 0x400000010
(gdb)