[ticket/11144] Add missing {FORUM_NAME} variable

The template variable {FORUM_NAME} was missing from
the login page of a password protected forum

PHPBB3-11144

phpBB/posting.php

@@ -196,6 +196,7 @@ if ($post_data['forum_password'])
 {
 	login_forum_box(array(
 		'forum_id'			=> $forum_id,
+		'forum_name'        => $post_data['forum_name'],
 		'forum_password'	=> $post_data['forum_password'])
 	);
 }