bug#39546: 28.0.50; Do not require subr-x at run time

[Tino Calancha]

On Mon, 10 Feb 2020, Eli Zaretskii wrote:

> > From: Tino Calancha <tino.calancha@gmail.com>
> > Date: Mon, 10 Feb 2020 18:26:13 +0100 (CET)
> > cc: Tino Calancha <tino.calancha@gmail.com>, 39546@debbugs.gnu.org,
> >     larsi@gnus.org, michael.albinus@gmx.de, tsdh@gnu.org
> >
> > On Mon, 10 Feb 2020, Eli Zaretskii wrote:
> >
> > > subr.el is preloaded, so doing that will enlarge the Emacs memory
> > > footprint.  Is that function important enough to have it preloaded?
> > According with its usage at Emacs source (only at json.el) I'd say
> > the answer to your question is: not worth to be at subr.el.
>
> That's what I thought.  So I suggest to find another file to host this
> function, if we want subr-x.el to have only macros and defsubst's.

replace.el is a good agreement between subr-x.el (it's a defun, so 
it doesn't fit well there) and subr.el.

As subr.el, replace.el is also loaded at start time, but it's ~ half size,
and more important than that, it's all about replacing in Emacs.