r600g/llvm: rework handling of the constants

Vincent Lejeune:
  - tgsi to llvm now emits pointers for constants

Tom Stellard:
  - Only use texture cache for vtx fetch with compute shaders
  - Change address space used for constant loads to match LLVM
    backend.

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
3 files changed