clover: handle libclc shader (v3)

clover: handle libclc shader (v3)

This works by taking the spirv produced by libclc which contains
a lot of mangled function entrypoints identified with LinkageAttribute decorations.

This patch just sets up clover to load the libclc blob and convert it to
library nir, and support inlining application nir with calls to libclc.

v2: Add a disk cache support for this object, to avoid the spirv parsing
overheads each time. move spirv->nir to lazy instantiation to avoid
the mess with glsl types and constructor ordering.
v3: make disk cache optional

v1-Reviewed-by: Jesse Natalie <jenatali@microsoft.com>

Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6035>