Fixed bug #64821 Custom Exceptions crash when internal properties overridden

If user inherits Exception and overrides the properties to arbitrary data types,
or simply doesn't run parent::__construct(), here we go. Just convert everything
to the appropriate data type, like Exception::__toString() does.
Merge branch 'PHP-5.3' into PHP-5.4

* PHP-5.3:
  Fixed bug #64821 Custom Exceptions crash when internal properties overridden
updated NEWS