Move DisconnectNodes logic to private method.

src/net.h

@@ -336,6 +336,7 @@ private:
     void ThreadOpenConnections(std::vector<std::string> connect);
     void ThreadMessageHandler();
     void AcceptConnection(const ListenSocket& hListenSocket);
+    void DisconnectNodes();
     void NotifyNumConnectionsChanged();
     void ThreadSocketHandler();
     void ThreadDNSAddressSeed();