[libc++] Undeprecate POSIX STREAM macros. (#88296)

LWG3869 Deprecate std::errc constants related to UNIX STREAMS

deprecates the POSIX macros ENODATA, ENOSR, ENOSTR, and ETIME. These
were deprecated in libc++ in
https://github.com/llvm/llvm-project/pull/80542

. Based on the post
commit feedback the macro are no longer deprecated. Instead libc++
leaves the deprecation to the provider of errno.h.

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Co-authored-by: Hristo Hristov <zingam@outlook.com>
Co-authored-by: Louis Dionne <ldionne.2@gmail.com>