[clang] [llvm] [Clang][C++23] Core language changes from P1467R9 extended floating-point types and standard names. (PR #78503)

[M. Zeeshan Siddiqui via llvm-commits]

codemzs wrote:

> > @codemzs I want to make sure you saw the pending feedback. I think it would be great if we could land this for clang 21 :)
> 
> @cor3ntin I plan to address the feedback this weekend. I agree with you on aiming to get this in for clang 21, thank you for letting me know.

@cor3ntin I am really sorry for delay in my response. I have been busy with work on several time sensitive projects that just happen to come one after the other. I can prioritize checking-in this PR if you think we still have a chance to get in for clang 21? Even if not I fully plan on closing this as soon as possible. 

@AaronBallman I'd like to get your thoughts as well?

https://github.com/llvm/llvm-project/pull/78503