gengenrtl needs to link with libintl

[DJ Delorie]

> I am still a puzzled as to what generator programs can and can't link
> with.

The problem is detecting what's available, since autoconf doesn't
check the build system when build!=host.  At the moment, anything that
will run on the build system can't link against anything in the build
tree, and we don't autoconf-test the build system, so we have to be
particularly careful to write portable code.  In general, generator
programs shouldn't link with *anything* if possible.

I think the problems we're seeing now are due to a partial infection
of a build-system build with host-system config.h from libiberty,
because of the obstack hack.  A build-libiberty should solve that
problem neatly, and perhaps pave the way to better handling of the
build system configuration.  We'll have to see how it pans out.