bug#40003: 27.0.70; Windows build is without jansson support

[Eli Zaretskii]

> From: Phillip Lord <phillip.lord@russet.org.uk>
> Cc: Eli Zaretskii <eliz@gnu.org>,  Ivan Yonchovski <yyoncho@gmail.com>,
>   40003@debbugs.gnu.org
> Date: Mon, 22 Jun 2020 16:53:25 +0100
> 
> I am trying to build this against Emacs-28 at the moment. What test can
> I run on Emacs-28 to let me know if it has worked?

  cd test && make src/json-tests

If this says tests were not skipped, you've succeeded, and your Emacs
uses the libjansson library.

> After that, the decision is what to do for Emacs-27. I can add the
> dependency, but it will require rebuilding the deps file which will
> update *all* of the dependencies. Not a big problem in one sense, but we
> are in the pre-release test phase, IIUC.

I'd say go for it.  I don't expect trivial changes in the dependencies
to affect Emacs.

Thanks.