For the d3d12 and shader runner tests I've been using an environment variable to specify the path to DXC, HLSL source declarations in d3d12.c, and an `[enable]` directive in shader runner. Are those acceptable for upstream?
It's of course not ideal to depend on DXC/dxcompiler for the DXIL shader runner tests like that, but I think we can work with that, yes. There's some precedent as well, because we can also use d3dcompiler for running shader runner tests.
In terms of the checksum, the most practical way to make that work in the shader runner is probably to introduce a flag like "VKD3D_SHADER_PARSE_DXBC_IGNORE_CHECKSUM" for vkd3d_shader_parse_dxbc(), then use that to parse the DXBCs produced by Linux DXC, and use vkd3d_shader_serialize_dxbc() to create a DXBC blob to pass to d3d12/vkd3d. Also, would we need to use DXC, or could we use the dxcompiler library?