llvmpipe OpenCL support (clover/nir)
This series enables OpenCL on llvmpipe with clover using NIR. It's passes a bunch of the piglit tests within the current boundaries of the spir-v/NIR/OpenCL implementation.
I think it would be very useful later to have CI run against clover and CL in general.
It it based on my !2933 (merged) which is needed to bring llvmpipe NIR up to par for GL.