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

[Eli Zaretskii]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: tino.calancha@gmail.com,  24518@debbugs.gnu.org
> Date: Sat, 24 Sep 2016 21:13:01 +0200
> 
> > I believe my recent commit fixed all of the above.
> 
> No, it doesn't make sense to ask for the marker.

That's not a problem that needed fixing.  It's an optional feature, so
users who see no sense in it could simply not invoke the command with
an argument.