Re: hard-locale: make multithread-safe

[Paul Eggert]

Thanks, this change looks fine to me.

I do have a qualm in that coreutils (and I assume others) interpret !hard_locale
(LC_COLLATE) as meaning that the locale is unibyte and uses native byte
comparison. As I recall on some platforms (macOS maybe?), the C locale uses
UTF-8 so this interpretation isn't correct.

This qualm is present both before and after the change, though. Perhaps the
problem should be documented, but that could be the subject of a later patch.