WIP: lavapipe: float_controls
This passes around 97% of CTS, but it fails cases like dEQP-VK.spirv_assembly.instruction.graphics.float_controls.fp32.input_args.denorm_mmuls_var_preserve_vert
I think because llvmpipe/gallivm have no concept of setting a specific denorm mode, and so the alus are broken. Not an expert though.
I'm probably not going to do anything else with this, but it should be a good base if @airlied or @sroland are interested in plumbing that part through.