[libc-commits] [libc] [libc] Remove specific nan payload in math functions (PR #79165)

[via libc-commits]

lntue wrote:

> @lntue can you PTAL? If this patch is correct this means we can completely remove `FPBits::build_nan`
> 
> edit: You can review [2fdf373](https://github.com/llvm/llvm-project/commit/2fdf3731f2c5de40c0faccb46cdf0818c42893a1) only, the other one you already reviewed but I had to push force (conflict -> rebase).

Yes, most of the time we only need `build_quiet_nan`, but there might be some rare cases that we need signaling nan.  I guess we can remove `build_nan`, and only use `build_quiet_nan` + `build_signaling_nan` to be explicit.

https://github.com/llvm/llvm-project/pull/79165