bug#59935: 29.0.60; project-list-buffers is slow

[Dmitry Gutov]

On 11/12/2022 19:49, Eli Zaretskii wrote:
> Thanks, but I hope you don't intend to ask to install this on the
> release branch.  And changing back the signature of
> list-buffers-noselect is extremely problematic, even though we changed
> it only for Emacs 29.

The problem with *not* changing it, is we don't seem to be able to use 
the new calling convention to implement project-list-buffers working 
without this performance problem.

We could just use the old (private) interface, but then the new calling 
convention will be left without any users at all. We extended it in 
order to implement this feature anyway.