[libc-commits] [libc] first trailing zero (PR #81526)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

note to reviewers; this is a stacked commit on top of #81502. Only https://github.com/llvm/llvm-project/pull/81526/commits/be816525a7bb42297c625a58fb55af5e90aa1425 and subsequent commits should be reviewed here.

https://github.com/llvm/llvm-project/pull/81526