[libclc] [libclc] Fix using normalizad triple for the directory name (PR #194607)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:

> Does anyone know how we are supposed to handle the triples like `clspv`? My understanding is that this is entirely for a Google project, but I do not know why we use a value that isn't a triple instead of keying it off of `spirv64-unknown-vulkan` or something similar. Anyone who who I'd ask for that? I think it should be updated now that libclc is moving to using the LLVM_RUNTIME_TARGETS method.

I was previously pinging @rjodinchr about clspv changes.

https://github.com/llvm/llvm-project/pull/194607