bug#24518: 25.2.50; dired-mark-extension with prefix arg fails

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Date: Sat, 24 Sep 2016 23:06:46 +0900 (JST)
> cc: Andreas Schwab <schwab@linux-m68k.org>, tino.calancha@gmail.com, 
>     24518@debbugs.gnu.org
> 
> Feel free to fix the bug as you wish and push it to the repository.
> I don't want to do it myself, because i don't want my name appear in
> the git log as the author of that solution.

Done.