Added using NodeCallback::run() to avoid warnings

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14246 16af8721-9629-0410-8352-f15c8da7e697

include/osg/ClusterCullingCallback

@@ -33,6 +33,9 @@ class OSG_EXPORT ClusterCullingCallback : public Drawable::CullCallback, public
 
         META_Object(osg,ClusterCullingCallback);
 
+        // use the NodeCallbacks implementation of run.
+        using NodeCallback::run;
+
         /** Computes the control point, normal, and deviation from the
           * given drawable contents. */
         void computeFrom(const osg::Drawable* drawable);