Fixed warning message if QMetaObjectCleanUp::setMetaObject is invoked twice.

If the passed object is the same, the warning message is not displayed any more.
If the passed object is different, a message is still displayed.
This resolves bug 1947.
(cherry picked from commit a401ecd325)

src/kernel/qmetaobject.cpp

@@ -1244,7 +1244,7 @@ QMetaObjectCleanUp::~QMetaObjectCleanUp()
 void QMetaObjectCleanUp::setMetaObject( QMetaObject *&mo )
 {
 #if defined(QT_CHECK_RANGE)
-    if ( metaObject )
+    if (metaObject && metaObject != &mo)
 	qWarning( "QMetaObjectCleanUp::setMetaObject: Double use of QMetaObjectCleanUp!" );
 #endif
     metaObject = &mo;