message: Rename _bid to buttonId
diff: @@ -401,9 +401,9 @@ bool doYesNoMessage(const std::string& title, const std::string msg)
  nullptr
  };
  - int _bid = 0;
  - SDL_ShowMessageBox(&messageboxdata, &_bid);
  - yes = (_bid == 1);
  + int buttonId = 0;
  + SDL_ShowMessageBox(&messageboxdata, &buttonId);
  + yes = (buttonId == 1);
  #endif
  return yes;
  