bug#59137: [PATCH] To minor changes related to overlays

[Eli Zaretskii]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Wed, 30 Nov 2022 02:28:09 +0100
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>, Eli Zaretskii <eliz@gnu.org>, 
> 59137@debbugs.gnu.org
> 
> Matt Armstrong <matt@rfc20.org> writes:
> 
> > The admittedly redundant NULL check done by itree_empty_p does not
> > change semantics or cause harm.  mark_overlays in alloc.c is a recursive
> > function so it handles NULL itself, hence the NULL check was omitted in
> > the original code.
> 
> Thanks.
> 
> I guess as this is a minor cleanup this should go to master at this point.

I agree.  We can always cherry-pick if we find a good reason.