DolphinQt: Move graphics config to main Settings window.

Source/Core/DolphinQt/Config/SettingsWindow.h

@@ -7,6 +7,7 @@
 
 class QStackedWidget;
 class QListWidget;
+class MainWindow;
 
 // A settings window with a QListWidget to switch between panes of a QStackedWidget.
 class StackedSettingsWindow : public QDialog
@@ -34,6 +35,7 @@ private:
 enum class SettingsWindowPaneIndex : int
 {
   General = 0,
+  Graphics,
   Controllers,
   Interface,
   Audio,
@@ -47,7 +49,7 @@ class SettingsWindow final : public StackedSettingsWindow
 {
   Q_OBJECT
 public:
-  explicit SettingsWindow(QWidget* parent = nullptr);
+  explicit SettingsWindow(MainWindow* parent);
 
   void SelectPane(SettingsWindowPaneIndex);
 };