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

[Romaric Jodin via cfe-commits]

rjodinchr wrote:

`clspv` doesn't actually utilize the `clspv--` or `clspv64--` triples; since it simply consumes the generated binaries, those names are arbitrary and can easily be updated.

**The primary requirement is keeping a method to target the specific `clspv` path within `libclc`.**

Once inside the `clspv` workflow, the system actually relies on `spir-unknown-unknown` and `spir64-unknown-unknown` triples. While some cleanup might be necessary, that remains an internal task for the `clspv` side.

cc @alanbaker @dneto for visibility.

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