Don't use libintl in glib

Patch out the chunk of GLib's configure script that looks for
libintl. Take care of fallout in a couple of places in GLib
sources. The end result is that GLib doesn't use any libintl (gettext
etc) functionality. Which is nice, as we then shouldn't need to build
gettext. No functionality should be lost, as we weren't delivering any
GLib message catalogs anyway, so none of the gettext calls at least
here would ever have found any localised messages.