Plug leaks in tests/auto/dbus

In tst_QDBusMetaObject::types(), hold a QMetaObject obtained from
QDBusMetaObject::createMetaObject() in a QScopedPointer instead of
leaking it. Use correct return value type.

This fixes the remaining errors in GCC 6.1 Linux ASan runs of
tests/auto/dbus.

Change-Id: I1df7f8e42d45f40ecf381fe7b684a8ab5ebee675
Reviewed-by: Alex Blasche <alexander.blasche@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/auto/dbus/qdbusmetaobject/tst_qdbusmetaobject.cpp

@@ -370,8 +370,7 @@ void tst_QDBusMetaObject::types()
 
     QDBusError error;
 
-    QMetaObject *result = QDBusMetaObject::createMetaObject("local.Interface", xml,
-                                                            map, error);
+    const QScopedPointer<QDBusMetaObject> result(QDBusMetaObject::createMetaObject("local.Interface", xml, map, error));
     QVERIFY2(result, qPrintable(error.message()));
 
     QCOMPARE(result->enumeratorCount(), 0);