nir: Add new variable modes for ray-tracing

If we were desperate to reduce bits, we could probably also use
shader_in/out for hit attributes as they really are an output from
intersection shaders and read-only in any-hit and closest-hit shaders.
However, other passes such as nir_gether_info like to assume that
anything with nir_var_shader_in/out is indexed using vec4 locations for
interface matching.  It's easier to just add a new variable mode.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6479>
6 files changed