Add support for Nvidia CG Toolkit

Packages describing “cg” as local USE flag

Package “cg” Flag Description
app-emulation/punes Add support for Nvidia CG Toolkit
dev-games/ogre NVIDIA toolkit plugin
dev-scheme/gauche-gl Enable NVidia Cg binding
sci-visualization/paraview Add support for nvidia's cg shaders

All packages providing a “cg” USE flag (4)