[clang] Clang: Drop float support from __builtin_elementwise_max (PR #180885)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> That's how I lean but I don't have a good idea for what the warning conditions would be. I don't think "warn on any float" is viable -- outside of a handful of edge cases, the function does what it says on the tin, right? And the edge cases aren't something we can catch statically in most cases, I believe.

Deprecation warning 

https://github.com/llvm/llvm-project/pull/180885