add QScopedPointerDeleteLater, a custom deleter for QObjects

This is a custom deleter for QObjects that are participating in an event
loop (e.g. waiting for signals to complete a task), which need to be
deleted using deleteLater() rather than just delete.

Change-Id: I3084ea28a6829a299c7400006c617fc23cf15160
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qscopedpointer.cpp

@@ -95,6 +95,9 @@ QT_BEGIN_NAMESPACE
        this handler for pointers that were allocated with \c{new []}.
     \li QScopedPointerPodDeleter - deletes the pointer using \c{free()}. Use this
        handler for pointers that were allocated with \c{malloc()}.
+    \li QScopedPointerDeleteLater - deletes a pointer by calling \c{deleteLater()}
+       on it. Use this handler for pointers to QObject's that are actively
+       participating in a QEventLoop.
     \endlist
 
     You can pass your own classes as handlers, provided that they have a public

src/corelib/tools/qscopedpointer.h

@@ -83,6 +83,17 @@ struct QScopedPointerPodDeleter
     static inline void cleanup(void *pointer) { if (pointer) free(pointer); }
 };
 
+#ifndef QT_NO_QOBJECT
+template <typename T>
+struct QScopedPointerObjectDeleteLater
+{
+    static inline void cleanup(T *pointer) { if (pointer) pointer->deleteLater(); }
+};
+
+class QObject;
+typedef QScopedPointerObjectDeleteLater<QObject> QScopedPointerDeleteLater;
+#endif
+
 template <typename T, typename Cleanup = QScopedPointerDeleter<T> >
 class QScopedPointer
 {