[libclc] [libclc] Canonicalize 'clspv' to the 'spirv-unknown-vulkan' triple (PR #196351)

[Romaric Jodin via cfe-commits]

rjodinchr wrote:

> > Adding `spirv32` everywhere we have `spirv64` and targeting `spirv32-unknown-vulkan` works fine for `clspv`.
> 
> So, the PR works in your case? Let me know if you need anything else changed.

No it does not work in its actual shape. We need to add `spirv32` everywhere we have `spirv64` in the cmake files.

https://github.com/llvm/llvm-project/pull/196351