bug#62762: 'make' often errors with "Org version mismatch" after pulling a new version of the code

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: dmitry@gutov.dev, bzg@gnu.org, 62762@debbugs.gnu.org
> Date: Thu, 13 Apr 2023 15:05:21 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> See the attached.
> >> On Emacs side, `org--built-in-p' will need to be set during compilation.
> >
> > LGTM, will soon incorporate this in our build system.
> 
> Once you confirm that my patch + your build system update fixes the
> problem, I will push to Org bugfix and bump a minor bugfix release.

I've now installed the change on master.

I wonder why org--built-in-p is a defconst, though: shouldn't it be a
defvar instead?