fixed disconnect; gcc warning

libp2p/Host.cpp

@@ -182,6 +182,7 @@ void Host::disconnectPeers()
 	}
 
 	delete m_upnp;
+	m_upnp = nullptr;
 }
 
 void Host::seal(bytes& _b)
@@ -212,7 +213,7 @@ void Host::determinePublic(string const& _publicAddress, bool _upnp)
 		clog(NetNote) << "External addr:" << m_upnp->externalIP();
 		int p;
 		for (auto const& addr : m_peerAddresses)
-			if (p = m_upnp->addRedirect(addr.to_string().c_str(), m_listenPort))
+			if ((p = m_upnp->addRedirect(addr.to_string().c_str(), m_listenPort)))
 				break;
 		if (p)
 			clog(NetNote) << "Punched through NAT and mapped local port" << m_listenPort << "onto external port" << p << ".";