Fix Qt4 build

Strangely no problems on Qt5 without those declarations.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/subsurfacewebservices.h

@@ -102,6 +102,13 @@ class UserSurveyServices : public WebServices {
 public:
 	void sendSurvey(QString values);
 	explicit UserSurveyServices(QWidget *parent = 0, Qt::WindowFlags f = 0);
+private
+slots:
+	// need to declare them as no ops or Qt4 is unhappy
+	virtual void startDownload() { }
+	virtual void startUpload() { }
+	virtual void buttonClicked(QAbstractButton *button) { }
+
 };
 
 #ifdef __cplusplus