bug#20728: 25.0.50; grep and grep-find templates should have a place holder for the --color argument

[Eli Zaretskii]

> Cc: 20728@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Thu, 4 Jun 2015 20:46:18 +0300
> 
> On 06/04/2015 08:16 PM, Eli Zaretskii wrote:
> 
> > With a placeholder that is %s, like we do with all the rest when we
> > format a string.
> 
> Then it'll also be a template. With a downside of using different 
> placeholder than the other templates in grep.el.

I see a lot of %s in grep.el, so it's not like this is a precedent
that we didn't have before.  That's the usual way we construct
variable-form commands in Emacs.  Why should this one be different?