[llvm-branch-commits] [libcxx] release/18.x: [libc++] Simplify the implementation of <stddef.h> (#86843) (PR #87374)

[Louis Dionne via llvm-branch-commits]

ldionne wrote:

> As mentioned on #86843, this breaks using `-pedantic` in code that includes libc++ headers. Since this got cherry-picked, we also must cherry-pick #88214.

I just started that process here: https://github.com/llvm/llvm-project/pull/88214#issuecomment-2050203419

https://github.com/llvm/llvm-project/pull/87374