Added CMake support for specifying what OpenGL target and features that the OpenSceneGraph build should use.

Added use of the new Cmake generated #define's for optionally compiling parts of the OpenSceneGraph's OpenGL support for the various OpenGL targets

src/osg/ShadeModel.cpp

@@ -12,6 +12,7 @@
 */
 #include <osg/GL>
 #include <osg/ShadeModel>
+#include <osg/Notify>
 
 using namespace osg;
 
@@ -27,5 +28,9 @@ ShadeModel::~ShadeModel()
 
 void ShadeModel::apply(State&) const
 {
+#ifdef OSG_GL_FIXED_FUNCTION_AVAILABLE
     glShadeModel((GLenum)_mode);
+#else
+    osg::notify(osg::NOTICE)<<"Warning: ShadeModel::apply(State&) - not supported."<<std::endl;
+#endif
 }