Description:
------------
empty()/isset() doesn't work (returns opposite of expected) on superglobals when used inside functions.

Reproduce code:
---------------
<?php

// view script with: test.php?foo=bar

function test()
{
    if (!empty($_GET))
    {
        print_r($_GET);
    }
}

test();

?>

Expected result:
----------------
When run with something populating $_GET, I expect to see a proper printout from the print_r().

Actual result:
--------------
Nothing.