bug#69709: `sort` interface improvement and universal ordering predicate

[Daniel Mendler]

Mattias Engdegård <mattias.engdegard@gmail.com> writes:

> 25 mars 2024 kl. 12.11 skrev Mattias Engdegård <mattias.engdegard@gmail.com>:
>
>> The plan is to add scratch/sort-key to master in a few days if no serious 
>> issues turn up.
>
> Plan executed.

Thank you for this excellent improvement of the sort function! I would
like to back-port the new feature in the Compat library, specifically in
the emacs-30 branch of the Compat repository. I've seen you mentioned
some pure Lisp code, implementing the new feature, in a slower, but
backward compatible way, which we could perhaps use?

Daniel