[Mesa-dev] ARB_shader_subroutine - now explicit!

[Dave Airlie]

So I revisited ARB_shader_subroutine again today, and noticed
it was lacking wrt ARB_explicit_uniform_location thanks to some
piglits from Igalia/Intel.

So I've added support for that, cleaned up some things,
like calculating the compatible shaders for a uniform at link
time, stopped the dead code from eliminating subroutine 
uniforms so the queries continue to work,

I've enabled tessellation bits where it makes sense as well.

This series just enables it for gallium, I have the i965
changes to work on haswell ready as well, they are quite trivial.

Since we have games actively depending on this, it would be
nice to get it merged, so I don't spend more time rebasing 
than fixing.

Dave.