Description:
------------
Hello,

The PHP interpreter crashes with "Segmentation fault: 11" if the __clone() function is overriden to clone the object iself creating an infinite recursive call.

Test script:
---------------
<?php

class Crash {
  public function __clone() {
    return clone $this;
  }
}

$crash_obj = new Crash();

clone $crash_obj;


Expected result:
----------------
The interpreter should suicide gracefully when hits the stack size limit.

Actual result:
--------------
Segmentation fault: 11