Description:
------------
When I try to compile and load file defining class which   
inherits from class inheriting from builtin Exception 
class, PHP throws a fatal error.  

Reproduce code:
---------------
<?php  
class RuntimeException extends Exception  
{  
}  
  
class InvalidParamException extends RuntimeException  
{  
}  
?>  

Expected result:
----------------
No error.  

Actual result:
--------------
"Fatal error: Cannot override final method 
Exception::__clone()"