[3/5] WineD3D: Fix D3DFMT_R32F, R16F, G16R16F, ... in the pixel shader

[Stefan Dösinger]

> I forgot to mention this in my previous mail, but if we're going to
> change the color fixup code, we should really integrate it properly
> into the backend. Ie, shader_glsl_get_sample_function() and the ARB
> equivalent should be aware of the format conversion, in order to
> prevent having to swizzle from components that aren't available, like
> can happen with WINED3DFMT_L6V5U5.
Agreed. Although I think there was a reason why we did not do that when we
implemented the current structure of the color conversion code to replace a
hacky ARB integration of the color conversion.