Description:
------------
functions that accept callbacks do not look up the current namespace when searching for the callback name. I have observed this with register_shutdown_function() and pcntl_signal() but it's probably more than these two.

sample code below works if we pass the fqn, ie: register_shutdown_function("test\\shutdown");

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

namespace test;

function shutdown() {

        echo "bye\n";

}

register_shutdown_function("shutdown");

?>


Expected result:
----------------
bye

Actual result:
--------------
Warning: register_shutdown_function(): Invalid shutdown callback 'shutdown' passed in /root/php-5.3.0alpha3/ext/pcntl/- on line 11