Fix: [Network] send map to next client if current client disconnects

Also terminate creating of the savegame, as the client is gone,
there really is no need for that anymore.

(cherry picked from commit 8d199b1bbc)

src/network/network_server.h

@@ -89,6 +89,8 @@ public:
 	NetworkRecvStatus CloseConnection(NetworkRecvStatus status) override;
 	void GetClientName(char *client_name, const char *last) const;
 
+	void CheckNextClientToSendMap(NetworkClientSocket *ignore_cs = nullptr);
+
 	NetworkRecvStatus SendMap();
 	NetworkRecvStatus SendErrorQuit(ClientID client_id, NetworkErrorCode errorno);
 	NetworkRecvStatus SendQuit(ClientID client_id);