Codechange: refactor CheckGameCompatibility() from existing function

Later commits use this function in other places too.

src/network/core/game_info.h

@@ -93,6 +93,7 @@ extern NetworkServerGameInfo _network_game_info;
 
 const char *GetNetworkRevisionString();
 bool IsNetworkCompatibleVersion(const char *other);
+void CheckGameCompatibility(NetworkGameInfo &ngi);
 
 void FillNetworkGameInfo(NetworkGameInfo &ngi);