bug#46256: [feature/native-comp] AOT eln files ignored if run from build tree

[Eli Zaretskii]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Sat, 27 Feb 2021 21:58:25 +0000
> 
> > I suspect that the issue may be with parallel builds (note the "-j8"
> > above). Repeating the build with "-j1" appears to be building the
> > missing .eln files as expected.
> 
> Now that the -j1 build has completed (without error), all of the lisp
> files have been compiled AOT as expected, and running the resulting
> emacs does not rebuild any of those .eln files.
> 
> So I think there are still some other issues with dependencies and
> handling parallel builds, but this bug has been fixed.

Hmm... what would be the reason for parallel builds not work well on
MS-Windows? file sharing issues?

Does the async native compilation use temporary files, and if so, do
they reside in the same directory when multiple compilations are
running?