bug#69493: 30.0.50; Preferable choice of coding system on Japanese

[Eli Zaretskii]

> Date: Sat, 02 Mar 2024 08:44:56 +0900
> From: Kazuhiro Ito <kzhr@d1.dion.ne.jp>
> 
> When I call (set-language-environment "Japanese"), below code in
> lisp/language/japan-util.el is called.
> 
> (defun setup-japanese-environment-internal ()
>   (prefer-coding-system (if (memq system-type '(windows-nt ms-dos cygwin))
>                           'japanese-shift-jis
>                         'utf-8))
>   (use-cjk-char-width-table 'ja_JP))
> 
> 1. japanese-shift-jis is not proper coding system on Cygwin.
> 2. We have japanese-cp932, more appropriate coding system for DOS/Windows.
> 
> PLease see below patch.

Thanks, installed on the master branch, and closing the bug.

P.S. Please in the future try to submit patches in the format produced
by "git format-patch" -- that makes applying the patches much easier.