[libc] [llvm] [libc]Add proxy header hdr/float-macros.h (PR #88674)

[Nick Desaulniers via llvm-commits]

nickdesaulniers wrote:

@aniplcc I see this PR is currently marked as a draft. Please unmark it by clicking "Ready for review" when you're ready for us to take a look.

https://github.com/llvm/llvm-project/pull/88674