RTC: Fix config bug

trunk/src/app/srs_app_config.cpp

@@ -3785,7 +3785,8 @@ srs_error_t SrsConfig::check_normal_config()
                 && n != "play" && n != "publish" && n != "cluster"
                 && n != "security" && n != "http_remux" && n != "dash"
                 && n != "http_static" && n != "hds" && n != "exec"
-                && n != "in_ack_size" && n != "out_ack_size" && n != "rtc" && n != "nack") {
+                && n != "in_ack_size" && n != "out_ack_size" && n != "rtc" && n != "nack"
+                && n != "twcc") {
                 return srs_error_new(ERROR_SYSTEM_CONFIG_INVALID, "illegal vhost.%s", n.c_str());
             }
             // for each sub directives of vhost.