Partially revert decfae7b8a. Newer libtorrent RC_1_1 has added back the missing variables.

src/base/bittorrent/session.cpp

@@ -2294,6 +2294,7 @@ void Session::handleListenSucceededAlert(libt::listen_succeeded_alert *p)
 
 void Session::handleListenFailedAlert(libt::listen_failed_alert *p)
 {
+    boost::system::error_code ec;
     QString proto = "TCP";
     if (p->sock_type == libt::listen_failed_alert::udp)
         proto = "UDP";
@@ -2305,24 +2306,12 @@ void Session::handleListenFailedAlert(libt::listen_failed_alert *p)
         proto = "I2P";
     else if (p->sock_type == libt::listen_failed_alert::socks5)
         proto = "SOCKS5";
-
-#if LIBTORRENT_VERSION_NUM < 10100
-    boost::system::error_code ec;
     qDebug() << "Failed listening on " << proto << p->endpoint.address().to_string(ec).c_str() << "/" << p->endpoint.port();
     Logger::instance()->addMessage(
                 tr("qBittorrent failed listening on interface %1 port: %2/%3. Reason: %4.",
                    "e.g: qBittorrent failed listening on interface 192.168.0.1 port: TCP/6881. Reason: already in use.")
                 .arg(p->endpoint.address().to_string(ec).c_str()).arg(proto).arg(QString::number(p->endpoint.port()))
                 .arg(QString::fromLocal8Bit(p->error.message().c_str())), Log::CRITICAL);
-#else
-    qDebug() << "Failed listening on " << proto << p->listen_interface();
-    Logger::instance()->addMessage(
-                tr("qBittorrent failed listening on interface %1 [%2]. Reason: %3.",
-                   "e.g: qBittorrent failed listening on interface 192.168.0.1 [TCP]. Reason: already in use.")
-                .arg(QString::fromUtf8(p->listen_interface()))
-                .arg(proto)
-                .arg(Utils::String::fromStdString(p->error.message())), Log::CRITICAL);
-#endif
 }
 
 void Session::handleExternalIPAlert(libt::external_ip_alert *p)