Description:
------------
compact() does not "see" superglobals like $_GET/$_POST/etc. when called within a function (documentation says: "Any strings that are not set will simply be skipped.").

Tested on PHP versions 4.3.2, 4.3.9 (both Apache module and cli), 5.0.0, 5.0.1 (cli), 5.0.2, php5.1-dev-cli.

Reproduce code:
---------------
<?php
function foo()
{
    var_dump(compact('_GET', '_POST', '_SESSION', '_ENV', '_COOKIE', '_SERVER'));
}

var_dump(compact('_GET', '_POST', '_SESSION', '_ENV', '_COOKIE', '_SERVER'));
echo "\n------------------------\n";
foo();
?>

Expected result:
----------------
A dump of an array with indexes '_GET', '_POST' etc. pointing to the contents of the respective superglobals, then a dashed line, then the same dump again.

Actual result:
--------------
The expected dump, the dashed line, and a:0:{}.