bug#65187: 29.1; right edge of wide image can not be displayed in image-mode

[Eli Zaretskii]

> From: awrhygty@outlook.com
> Cc: michael_heerdegen@web.de,  65187@debbugs.gnu.org
> Date: Wed, 16 Aug 2023 12:26:41 +0900
> 
> I am using Windows PC with settings:
>   system->display->scaling and layout->125%
> 
> Changing the value to 100% and testing with a new instance of emacs,
> I can view the right red line with typing 'C-e'.
> Typing many 'C-f's works, too.

Thanks, I hope I've fixed this now on the emacs-29 branch.