wined3d: Allow vertex shaders to generate GLSL shaders [Take Two]

[Ivan Gyurdiev]

Jason Green wrote:
> This is a resend of the earlier patch, with one addition:
> - previously, the line to alias the program.env[] to C[] was done in
> the vertex shaders since that was the only function that needed them
> (and it needs to be done to support relative addressing).  However,
> with PS 2.0+, pixel shaders now need to be able to use relative
> addressing as well.  This can't be done with ARB_fragment_program, but
> it can be done with GLSL, so for consistency, we are now aliasing the
> program.env[] array to C[] for both ps & vs.
I think I've mislead you here (sorry)... the relative addressing on PS 
3.0+ is on input registers, against aL, not on constants. I think it 
allows you to read the inputs in a loop against the loop counter. 
According to spec, pixel shader constants still do not allow relative 
addressing. So, this constant aliasing thing... we likely don't need 
this in pixel shaders. However, I still think that it'd be nice to use 
the same names (so we can share more code), and put this kind of 
initialization in baseshader if possible. From that point of view I 
agree w/ the patch, as long as nothing breaks.