[libc] [llvm] [libc][NFC] Use user defined literals to build 128 and 256 bit constants. (PR #81746)

[Guillaume Chatelet via llvm-commits]

gchatelet wrote:

I used this function and updated the documentation
https://sagecell.sagemath.org/?q=neiiww

I haven't checked the scripts but they should be just a typo away from working 😅

https://github.com/llvm/llvm-project/pull/81746