[clang] Clang: Add elementwise minnum/maxnum builtin functions (PR #129207)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> > Needs the documentation updates in clang language extensions with the other elementwise builtins, and a release note
> 
> Documentation updated. And ReleaseNotes is submitted as a new PR: #131977

Best to keep the note about the new builtins here. The PR mentioning the other changes is separate from this standalone addition 

https://github.com/llvm/llvm-project/pull/129207