Add missing "We mean it" comments to private headers.

Change-Id: If81a5e1db0fe93377e7cc54a78b01c50b44abe57
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>

src/corelib/global/qhooks_p.h

@@ -35,6 +35,17 @@
 #ifndef QHOOKS_H
 #define QHOOKS_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtCore/qglobal.h>
 
 QT_BEGIN_NAMESPACE

src/platformsupport/dbusmenu/qdbusmenuadaptor_p.h

@@ -45,6 +45,17 @@
 #ifndef DBUSMENUADAPTOR_H
 #define DBUSMENUADAPTOR_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #include <QtCore/QObject>
 #include <QtDBus/QtDBus>
 #include "qdbusmenutypes_p.h"

src/platformsupport/dbusmenu/qdbusplatformmenu_p.h

@@ -33,6 +33,17 @@
 
 #ifndef QDBUSPLATFORMMENU_H
 #define QDBUSPLATFORMMENU_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
 //
 //  W A R N I N G
 //  -------------

src/platformsupport/dbustray/qstatusnotifieritemadaptor_p.h

@@ -45,6 +45,17 @@
 #ifndef QSTATUSNOTIFIERITEMADAPTER_P_H
 #define QSTATUSNOTIFIERITEMADAPTER_P_H
 
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
 #ifndef QT_NO_SYSTEMTRAYICON
 
 #include <QtCore/QObject>