Description:
------------
When __halt_compiler() is seen for the second time, PHP displays a message saying:

Notice: Constant __COMPILER_HALT_OFFSET__ already defined in ...

Although it cannot happen in a single file, it can happen when including two files containing an __halt_compiler() directive.

The constant should be undefined before calling REGISTER_MAIN_LONG_CONSTANT("__C
OMPILER_HALT_OFFSET__", zend_get_scanned_file_offset(TSRMLS_C), CONST_CS) in zend_language_parser.y but I haven't found any function  to undefine a constant...


Reproduce code:
---------------
* File a.php contains :

<?php
include 'b.php';
include 'c.php';

* File b.php and c.php both contain :

<?php
echo __FILE__."\n";
__halt_compiler();
data

* Run a.php

Expected result:
----------------
/depot/divers/flp/tmp/b.php
/depot/divers/flp/tmp/c.php


Actual result:
--------------
/depot/divers/flp/tmp/b.php

Notice: Constant __COMPILER_HALT_OFFSET__ already defined in /depot/divers/flp/tmp/c.php on line 3
/depot/divers/flp/tmp/c.php