[bug#57122] [PATCH] build-system: emacs: Use new function for autoloads generation

[Morgan Smith]

So the FreeBSD guys had the same issue but actually bothered to notify
upstream so the issue has been fixed:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=57200

That doesn't mean we shouldn't look into using a non-deprecated function
though.  Earlier I did try to use 'package-generate-autoloads' as that
seems like the ideal function to use but it adds the following string to
the loaddefs file:

"(add-to-list 'load-path (directory-file-name
                     (or (file-name-directory #$) (car load-path))))"

This line would probably work fine but for some reason when I tried it,
it didn't properly substitute '#$' with the file name.  I'm not really
sure how to fix that.