This adds code for handling fixed function fragment processing with the
GL_ATI_fragment_shader extension. This is a sort-of programmable
interface for fragment processing at the level of shader model 1.4 in
d3d. This code is of use on r200, r250 and r280 cards(radeon 8500 to
9200) which do not support GL_ARB_fragment_program, but support pixel
shader 1.4 on Windows. This code is somewhat a counterpart to the
existing fragment processing code using GL_NV_register_combiners and
GL_NV_texture_shader.