SM3.0 requires 10 4 component float varyings for passing stuff between
vertex and pixel shaders. GF7 and earlier report 8 generic varyings +
gl_Color and gl_SecondaryColor in GLSL. This patch allows us to use
gl_Color and gl_SecondaryColor to get 2 extra varyings, which some
games, like C&C3 with highest gfx settings, require.