v3d/compiler: handle compact varyings

We are going to need this in Vulkan because the SPIR-V compiler
defines clip distances as a single compact array of scalars, so
our compiler needs to know what to do with them.

Reviewed-by: Alejandro PiƱeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6022>
2 files changed