[libclc] libclc: Replace nextafter implementation (PR #186082)

[Romaric Jodin via cfe-commits]

rjodinchr wrote:

> Fixed by https://github.com/llvm/llvm-project/pull/187358

Have you been able to reproduce the error? As far as I can see, this is not fixing anything on all the platforms I have tested that patch on.

Considering that you do not seem open to revert and move that implementation to a specific backend, I will bring back the old implementation only for clspv.

We will see in the future if other libclc users  will complain about it or if it is clspv specific.

https://github.com/llvm/llvm-project/pull/186082