Added support for using geometry shaders to align the quad diagonals with the local terrain

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14658 16af8721-9629-0410-8352-f15c8da7e697

include/osgTerrain/GeometryPool

@@ -113,6 +113,8 @@ class OSGTERRAIN_EXPORT GeometryPool : public osg::Referenced
     protected:
         virtual ~GeometryPool();
 
+        bool                    _useGeometryShader;
+
         OpenThreads::Mutex      _geometryMapMutex;
         GeometryMap             _geometryMap;