bug#42753: 26.3; `info-lookup.el': Add all manuals delivered by `emacs -Q', for `emacs-lisp-mode'

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  42753@debbugs.gnu.org,
>   drew.adams@oracle.com
> Date: Fri, 08 Oct 2021 16:33:11 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Or rename the index nodes in the manuals to all follow the same naming
> >> conventions...
> >
> > I think this alternative cannot fly, because many manuals are not
> > under our control.
> 
> They are integrated in the Emacs source tree, so we could negotiate with
> the maintainers. Even if we cannot change all manuals this way, the
> number of exceptions in info-lookup would decrease.

I meant the likes of Python manual, the glibc manual, and others.
Good luck negotiating with them.  And then there's always a
possibility that the user will want to add some manual we know nothing
about.

I think a better solution will be to be tolerant, i.e. look for nodes
that contain "index", and maybe also "function" or "variable", in them
regardless of the rest.