UI: Fix Q_PROPERTY compiling warnings

UI/qt-display.hpp

@@ -5,8 +5,8 @@
 
 class OBSQTDisplay : public QWidget {
 	Q_OBJECT
-	Q_PROPERTY(QColor displayBackgroundColor WRITE SetDisplayBackgroundColor
-			NOTIFY SetDisplayBackgroundColor)
+	Q_PROPERTY(QColor displayBackgroundColor MEMBER backgroundColor
+			WRITE SetDisplayBackgroundColor)
 
 	OBSDisplay display;
 
@@ -20,7 +20,8 @@ signals:
 	void DisplayResized();
 
 public:
-	OBSQTDisplay(QWidget *parent = 0, Qt::WindowFlags flags = 0);
+	OBSQTDisplay(QWidget *parent = nullptr,
+			Qt::WindowFlags flags = nullptr);
 
 	virtual QPaintEngine *paintEngine() const override;