bug#30943: save-hist creates massive cache file

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Cc: eliz@gnu.org,  30943@debbugs.gnu.org
> Date: Thu, 29 Mar 2018 14:08:30 -0400
> 
> 
> I think it's a reasonable feature request to ask that savehist be
> capable of dealing with additional variables that aren't automatically
> truncated (or if not it should be explicit about it).

That'd require people to register a function to do the truncation.  We
could, of course, provide a couple of default functions to do that
with "simple" variables.

> On the other hand, desktop is a superset of savehist and can can already
> do this (apparently, see desktop-globals-to-save).

Yep.

> I wonder if load should pay attention to large-file-warning-threshold
> somehow?

I actually find that to be a nuisance even for visiting files.  With
64-bit builds, this warning makes very little sense.