Integrate pinentry-mac into pinentry

[Daniel Kahn Gillmor]

On Fri 2015-11-27 12:49:37 -0500, Werner Koch wrote:
> On Fri, 27 Nov 2015 16:56, Mento at gpgtools.org said:
>> How should we handle the additional strings? Currently there are two
>> simple strings files for englisch and german in the macosx subdir.
>
> Pinentry must not have any strings.  All strings are provided by gnupg
> so that we have a consistent translation.  If you need a new string
> please ask for it.

fwiw, i've been working with pinentry for a while now and hadn't
explicitly understood this constraint (though it makes sense now that i
read it and think about it).

And pinentry does use gettext in pinentry/argparse.c and secmem/util.c
(both copied from other projects, so maybe we can ignore that?).

This also makes pinentry less easily useful for non-GnuPG projects (or
rather, requires that non-GnuPG projects provide well-localized strings
directly to pinentry instead of depending on its defaults).

It would be good to add this caveat to doc/HACKING so people better
understand the constraints for pinentry.

           --dkg