bug#81332: info/dir and INFO_NONMISC are not gated by DOCLANGS

> From: Vincent Belaïche <[email protected]>
> CC: "[email protected]" <[email protected]>, "[email protected]"
> 	<[email protected]>
> Date: Mon, 17 Aug 2026 11:39:58 +0000
> 
> Thank you for the lesson. I must admit I should have paid more attention. Isn't it however a strange way to make
> a dual output source document. Usually one has a single master file and passes some parameter to select what
> output one wants.
> I attached an example source.texi, compile it with commands
> 
>   texi2pdf  -o short.pdf source.texi
>   texi2pdf -t "@set FULL 1" -o long.pdf source.texi
> 
> in order to select reduced print-out or full print-out version. makeinfo also has some switch to set compile flags
> from the command line.
> 
> It would be easy to modify the example to force full version for all format other than PDF, just insert this below
> @setfilename
> 
>     @ifnottex
>     @set FULL 1
>     @end ifnottex

This is a different situation.  In the case of the Emacs manual, we
don't want to just produce along and a short version, we want to
produce either a single large manual, or two smaller ones, where the
second one includes sections omitted from the first one.  That cannot
be easily done with a single symbol and using @ifset, because the
second manual is a complete separate book, and should thus include its
own preamble, top-level menu, etc.