First step of refactoring the osg::Program management in osgTerrain::GeometryPool for better performance by placing default osg::Program and shader defines on a single StateSet below the osgTerrain::Terrain

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14704 16af8721-9629-0410-8352-f15c8da7e697

src/osgFX/MultiTextureControl.cpp

@@ -165,6 +165,7 @@ void MultiTextureControl::updateStateSet()
         }
 #endif
         stateset->addUniform(uniform.get());
+        stateset->setDefine("TEXTURE_WEIGHTS");
     }
 
     setStateSet(stateset.get());