Whilst I'm a big fan of not adding bloat to libc, I'd prefer to see
the functionality of the current libintl being added to it(*) -
setting aside the strerror() and signal name strings, which can be
easily supported using catgets(), libc contains a huge number of
diagnostics and error strings for which I'd consider the gettext()
interface the most convenient choice.

(*) This is not a suggestion to have libc export these interfaces -
    it should provide private interface names only, which could be
    used by other libraries as well; one of these libraries would be
    libintl which should provide the public interfaces, either aliased
    or wrapped.