bug#46837: Makefile dependencies for info files

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Cc: 46837@debbugs.gnu.org
> Date: Thu, 04 Mar 2021 13:53:14 -0500
> 
> Eli Zaretskii wrote:
> 
> > Is the fact that we now rebuild info/dir each time we run "make", even
> > if nothing else is rebuilt, part of this issue?
> 
> Probably. I can't reproduce that at 9e94509267. I did not try before.

Yes, it stopped now.  Thanks.