[v3] autoconf 2.59 fixups

[Bonzini]

> Automake, however, still has problems, see below. If somebody will be
> so kind as to tell me how to fixup this bit, I'll do that too.

Add -Wno-override to the automake options.

For po/Makefile.am, the two problematic lines are

DISTFILES = \
        Makefile.am Makefile.in string_literals.cc POTFILES.in $(PACKAGE).pot \
        $(LOCALE_IN)

You can change these to

EXTRA_DIST = string_literals.cc POTFILES.in $(PACKAGE).pot $(LOCALE_IN)

That file may however cause more barking.  It would be best to rewrite
it to use an automake conditional.

Paolo