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

> From: Vincent Belaïche <[email protected]>
> CC: "[email protected]" <[email protected]>
> Date: Tue, 4 Aug 2026 12:14:49 +0000
> 
> IMHO it is not such a good idea to have specific handling for some manuals. This makes makefiles more
> complex and hard to maintain.

I respectfully disagree.

> Concerning Eli's point:
> 
> > THose 3 manuals must always be built and always be installed,
> > regardless of DOCLANGS.
> 
> I acknowledge that some manuals are really needed to be installed in a normal build. However, on the other
> hand, it should be possible for the aware user to configure the build without those manuals. I mean that it
> should be possible to build the Emacs executable on a machine on which the makeinfo tools are not available.
> The Emacs executable should be able to be installed, start and run w/o crashing even though the mandatory
> manuals are not installed. The user should get some error message, just like when some application's DLL is
> not there and you cannot load it, one gets an error message telling which DLL is missing.

When makeinfo is not available, it's a separate issue.  We already
provide the Info manuals as part of the release tarballs, so users who
build their own Emacs from a release tarball have no problem with
that.  For building from Git, makeinfo is a prerequisite.

> I understand that this is not the case, and currently makeinfo is a build prerequisite. Please don't take me
> wrong: I am not saying that the user should be anyhow encouraged not to compile & install the manuals. My
> point is that having some manual build mandated prevents code factorization in the makefiles, and that also
> prevents aware users to disable the manual building (at their own risks of not getting appropriate documentation
> when using Emacs) to get some minimalistic build. My recommendation is that makeinfo should just be highly
> recommended, but just like the TeX texinfo compiler, should not be absolutely mandated (meaning that it is ok if
> there is some trick like setting DOCLANGS to ' ' to disable manual compilation altogether).

I realize that this makes the build more complex, but having these 3
manuals is from my POV a requirement.  Emacs can run without them, and
will not crash, but we don't want such situation to happen just
because DOCLANGS was set to some value.