Fix bug that UDP port was incorrectly used in UDP tracker announce request

src/TrackerWatcherCommand.cc

@@ -300,7 +300,7 @@ TrackerWatcherCommand::createAnnounce(DownloadEngine* e)
       if (udpTrackerClient_ &&
           uri::getFieldString(res, USR_SCHEME, uri.c_str()) == "udp") {
         uint16_t localPort;
-        localPort = e->getBtRegistry()->getUdpPort();
+        localPort = e->getBtRegistry()->getTcpPort();
         treq =
             createUDPAnnRequest(uri::getFieldString(res, USR_HOST, uri.c_str()),
                                 res.port, localPort);