Fix the remaining include directives to follow Qt conventions

In public header files, always use this form to include Qt
headers: #include <QtCore/qwhatever.h>. The library prefix
is very convenient for non-qmake projects.

Change-Id: I033ae9defee2ae7d383d8f268a4d7923162ac49e
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Caroline Chao <caroline.chao@digia.com>

src/winextras/qwinfunctions.h

@@ -46,9 +46,9 @@
 #pragma qt_class(QWinFunctions)
 #endif
 
-#include <QObject>
-#include <QtWinExtras/qwinextrasglobal.h>
+#include <QtCore/qobject.h>
 #include <QtCore/qt_windows.h>
+#include <QtWinExtras/qwinextrasglobal.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -124,7 +124,7 @@ void Q_WINEXTRAS_EXPORT taskbarDeleteTab(QWindow *);
 
 #ifdef QT_WIDGETS_LIB
 
-#include <QWidget>
+#include <QtWidgets/qwidget.h>
 
 namespace QWinExtras
 {

src/winextras/qwintaskbarbutton.h

@@ -42,9 +42,8 @@
 #ifndef QWINTASKBARBUTTON_H
 #define QWINTASKBARBUTTON_H
 
+#include <QtCore/qobject.h>
 #include <QtWinExtras/qwinextrasglobal.h>
-#include <QObject>
-#include <QList>
 
 QT_BEGIN_NAMESPACE