Only clear the port when forcing SSL.

If using SSL_ONLY_LOGIN, any custom configured port should be taken
as the HTTP port since HTTPS is only used for login.

Bug: 13573

framework/Core/lib/Horde.php

@@ -443,9 +443,9 @@ public static function url($uri, $full = false, $opts = array())
                 break;
 
             case self::SSL_ONLY_LOGIN:
-                $server_port = '';
                 if (!empty($opts['force_ssl'])) {
                     $protocol = 'https';
+                    $server_port = '';
                 }
                 break;
             }