[libclc] [NFC][libclc] Refactor _CLC_*_VECTORIZE macros to functions in .inc files (PR #145678)

[Fraser Cormack via cfe-commits]

https://github.com/frasercrmck approved this pull request.

I was about to look into something along these lines but you beat me to it.

https://github.com/llvm/llvm-project/pull/145678