[clang] [clang][headers][Apple] Don't include_next float.h to avoid an unnecessary module dependency (PR #137432)

[Cyndy Ishida via cfe-commits]

https://github.com/cyndyishida approved this pull request.

AFAICT this seems like a good cleanup for detangling sdk dependencies where its safe to.

https://github.com/llvm/llvm-project/pull/137432