missing API for locale_t in <locale.h>

[Roland McGrath]

> In short, I'm asking for __current_locale_name to be made public. Or for
> nl_langinfo_l to be extended to support _NL_ADDRESS_NAME, _NL_CTYPE_NAME,
> _NL_MESSAGES_NAME, etc.

I'm inclined to add to nl_langinfo for this rather than adding a new entry
point.  Perhaps:

#define _NL_LOCALE(category)		_NL_ITEM (category, 0xffff)

so you use nl_langinfo (_NL_LOCALE (LC_MESSAGES)).