bug#57691: 29.0.50; image-tests failures

[Eli Zaretskii]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Fri, 9 Sep 2022 08:44:01 -0400
> Cc: 57691@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > If w32-use-native-image-API is nil, my Emacs uses libgif v5.1.0.  By
> > default, libgif is not used at all; instead, Emacs uses MS-Windows
> > native APIs in the system library gdiplus.dll to display GIF images.
> 
> Ah, I forgot about the native image stuff.
> 
> It seems to me that the test currently assumes that we do NOT use a
> native image API.
> 
> I don't know if we (1) need to adjust the delay on MS-Windows along the
> lines of what we do in image.c [see commit 3de2462da7], or (2) should
> change the test to set w32-use-native-image-API to nil, or (3) if we
> should just skip the test on MS-Windows.

What does that test check? why does it want to see the delay?

The native APIs support animated GIFs better than with libgif, so
artificially making changes of the delay for the single benefit of
running this test is not the best idea, IMO.