nir, st/mesa: improve NIR shader cache size, nir_strip removal
Along with !2561 (merged), this series reduces the size of serialized NIR. Not including GLSL and other metadata, the numbers are very favorable for this MR.
Borderlands 2 shaders only:
- The uncompressed size is reduced by 78%.
- The compressed size is reduced by 22%.
My whole shader-db:
- The uncompressed size is reduced by 88%.
- The compressed size is reduced by 25%.
Edited by Marek Olšák