Description:
------------
using global on super global causing segfault or memory corruption.

I have large codes which written in nasty way ;)
see Reproduce code

it works under php 4 and pre 5.1

please helpp

Reproduce code:
---------------
<?
session_start();

$_SESSION["sss"]=1000;
$sessvar = "_SESSION";

function abc()
{
        global ${$GLOBALS["sessvar"]};
        $biji = ${$GLOBALS["sessvar"]};

        print $biji["sss"];
}

abc();

Expected result:
----------------
no segfault 

Actual result:
--------------
1000*** glibc detected *** double free or corruption (fasttop): 0x083f4748 ***
Aborted

or segfault

#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7c15ef1 in raise () from /lib/tls/libc.so.6
#2  0xb7c1783b in abort () from /lib/tls/libc.so.6
#3  0xb7c4bff5 in __fsetlocking () from /lib/tls/libc.so.6
#4  0xb7c52587 in malloc_usable_size () from /lib/tls/libc.so.6
#5  0xb7c52a02 in free () from /lib/tls/libc.so.6
#6  0x081ed9a0 in shutdown_memory_manager (silent=0, full_shutdown=0) at /BUILD/src/php-5.1.1/Zend/zend_alloc.c:512
#7  0x081ccb98 in php_request_shutdown (dummy=0x0) at /BUILD/src/php-5.1.1/main/main.c:1287
#8  0x08289a81 in main (argc=2, argv=0xbfa77fb4) at /BUILD/src/php-5.1.1/sapi/cli/php_cli.c:1142