bug#43475: feature/native-comp; add a site-lisp path to comp-eln-load-path

[Ulrich Mueller <ulm@gentoo.org>]

>>>>> On Fri, 18 Sep 2020, Andrea Corallo wrote:

> Tom Gillespie <tgbugs@gmail.com> writes:

>> Suggestions from the previous discussion are
>> /usr/lib{,64}/emacs/site-eln and /usr/lib{,64}/emacs/site-lisp/eln.
>> 
>> If we want to mirror the way native-lisp is used for the system files
>> then ${libdir}/emacs/site-lisp and ${libdir}/emacs/site-lisp/native-lisp
>> are two other options.

> I think ${libdir}/emacs/site-lisp/native-lisp would be probably more
> future proof but I've no strong preference.

> Ulrich what would be your suggestion for this?

I'd prefer the shorter path. I believe it's very unlikely that there
could be other files in future that would be both lisp and architecture
dependent, i.e. that would be installed in ${libdir}/emacs/site-lisp/
as well. In other words, the additional subdirectory level would be
totally redundant.

So, my suggestion would be either ${libdir}/emacs/site-lisp/ or
${libdir}/emacs/site-eln/ with a slight preference for the second.

(Note that Gentoo would create another subdirectory when installing an
add-on elisp package, so the path would be (for example)
${libdir}/emacs/site-eln/${package_name}/.)