Qt: use QWidgetList when applicable

modules/gui/qt4/components/playlist/playlist.hpp

@@ -130,7 +130,7 @@ private:
 
     PLModel *model;
     QSignalMapper *mapper;
-    QList<QWidget*> buttons;
+    QWidgetList buttons;
     QList<QAction*> actions;
     LocationButton *btnMore;
     QMenu *menuMore;

modules/gui/qt4/components/simple_preferences.hpp

@@ -119,7 +119,7 @@ private:
 
     int number;
 
-    QList<QWidget *> optionWidgets;
+    QWidgetList optionWidgets;
     QStringList qs_filter;
     QButtonGroup *radioGroup;