Change window close/deallocation to match upstream

src/airport_gui.cpp

@@ -78,10 +78,11 @@ struct BuildAirToolbarWindow : Window {
 		this->last_user_action = WIDGET_LIST_END;
 	}
 
-	~BuildAirToolbarWindow()
+	void Close() override
 	{
 		if (this->IsWidgetLowered(WID_AT_AIRPORT)) SetViewportCatchmentStation(nullptr, true);
 		if (_settings_client.gui.link_terraform_toolbar) CloseWindowById(WC_SCEN_LAND_GEN, 0, false);
+		this->Window::Close();
 	}
 
 	/**
@@ -278,9 +279,10 @@ public:
 		if (selectFirstAirport) this->SelectFirstAvailableAirport(true);
 	}
 
-	virtual ~BuildAirportWindow()
+	void Close() override
 	{
 		CloseWindowById(WC_SELECT_STATION, 0);
+		this->PickerWindowBase::Close();
 	}
 
 	void SetStringParameters(int widget) const override