bug#48228: json-serialize should signal error when dll is not found [MS Windows]

[Eli Zaretskii]

> Cc: p.stephani2@gmail.com, 48228@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Tue, 4 May 2021 20:00:37 +0300
> 
> On 04.05.2021 19:44, Eli Zaretskii wrote:
> > OTOH, we will next have people asking why some libraries use one
> > paradigm and others another...
> 
> Why not make them use both paradigms?

Could be okay, but it is no longer a local change in json.c, it will
be something affecting a lot of use cases out there.

For example, trying to display an image when its library isn't
available currently shows a placebo, but it will signal an error under
your suggestion.  If people aren't worried about that, we could try
it.