bug#46790: 28.0.50; make install with native-comp branch

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 46790@debbugs.gnu.org, akrl@sdf.org
> From: Phil Sainty <psainty@orcon.net.nz>
> Date: Mon, 26 Apr 2021 02:28:08 +1200
> 
> On 26/04/21 1:28 am, Eli Zaretskii wrote:
> > In any case, what error messages do you see with async-start now?
> > can you show those messages in their entirety?
> 
> Perhaps something like this will help?
> 
> emacs --batch -f package-initialize -l async \
>   --eval "(message \"%s\" (executable-find \"emacs\"))" \
>   --eval "(pp (async-get (async-start (lambda ()
>           (list comp-eln-load-path (pdumper-stats))))))"

If my reading of async.el is correct, it invoces the inferior Emacs
like this:

    (setq async--procvar
          (async-start-process
           "emacs" (file-truename
                    (expand-file-name invocation-name
                                      invocation-directory))
           finish-func
           async-quiet-switch "-l"
           ;; Using `locate-library' ensure we use the right file
           ;; when the .elc have been deleted.
           (locate-library "async")
           "-batch" "-f" "async-batch-invoke"
           (if async-send-over-pipe
               "<none>"
             (with-temp-buffer
               (async--insert-sexp (list 'quote sexp)) (buffer-string)))))

Thierry, what does the below yield in the interactive session from
which you invoke async-start?

  M-: (file-truename (expand-file-name invocation-name invocation-directory)) RET