[libclc] [libclc] Move fmin/fmax to the CLC library (PR #128506)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:

Note @arsenm I didn't touch [amdgcn's fmin/fmax](https://github.com/llvm/llvm-project/blob/main/libclc/amdgcn/lib/math/fmin.cl) or [r600's](https://github.com/llvm/llvm-project/blob/main/libclc/r600/lib/math/fmin.cl) as I wasn't sure if any of that could be updated or at least unified. Would you be able to help there?

I note that the comments around the use of canonicalize mention sNAN, which isn't required by the spec.

https://github.com/llvm/llvm-project/pull/128506