ext/standard: Reject NUL bytes in dl()

[LamentXU123]

Similar to #21942 and #21871. The dl function in std extension now silently truncates from NUL bytes. That is

<?php$payload = "a\0/bcdefgh";
set_error_handler(function ($severity, $message) {
echo"warning: $message\n";
returntrue;
});
try {
var_dump(dl($payload));
} catch (ValueError$e) {
echo"ValueError: ", $e->getMessage(), "\n";
}

Will return:

warning: dl(): Unable to load dynamic library 'a'

not

warning: dl(): Unable to load dynamic library 'a/bcdefgh'

Reproduce here

This PR rejects parameters containing NUL bytes as we always do in other cases.