[libc-commits] [libc] [libc] add headers.txt for windows (PR #118675)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

@SchrodingerZhu if you have a windows build handy, can you please help test this out? This would be doing a fullbuild on windows.

https://github.com/llvm/llvm-project/pull/118675