Fix in for getopt alias ordering

The option get does not return the correct value when using aliasing and referencing the alias to get the option (even when the value is passed by the alias).

    $context = $this->newContext(array(
        'argv' => array(
            '-f',
        )
    ));
    $getopt = $context->getopt(array('f,foo'));
    $getopt->get('-f'); // Works
    $getopt->get('--foo'); // Fails

    $context = $this->newContext(array(
        'argv' => array(
            '--foo',
        )
    ));
    $getopt = $context->getopt(array('f,foo'));
    $getopt->get('-f'); // Works
    $getopt->get('--foo'); // Fails