Handle a bunch more clang warnings

gui/dialogs/IconPickerDialog.h

@@ -29,7 +29,10 @@ class IconPickerDialog : public QDialog
 public:
 	explicit IconPickerDialog(QWidget *parent = 0);
 	~IconPickerDialog();
+	#pragma clang diagnostic push
+	#pragma clang diagnostic ignored "-Woverloaded-virtual"
 	int exec(QString selection);
+	#pragma clang diagnostic pop
 	QString selectedIconKey;
 
 protected:

gui/dialogs/ProgressDialog.h

@@ -34,7 +34,11 @@ public:
 
 	void updateSize();
 
+	#pragma clang diagnostic push
+	#pragma clang diagnostic ignored "-Woverloaded-virtual"
 	int exec(ProgressProvider *task);
+	#pragma clang diagnostic pop
+
 	void setSkipButton(bool present, QString label = QString());
 
 	ProgressProvider *getTask();