Building a tarball with native-compilation support

[Eli Zaretskii <eliz@gnu.org>]

I think we have an unsolved issue for when we will release an Emacs
tarball that supports native-compilation: how to compile the preloaded
*.el files natively at build time.  This has to be done on the machine
where the tarball is built, because the *.eln files are
architecture-dependent, and thus cannot be in the source tarball.

Currently, compiling the preloaded *.el into *.eln is a side effect of
byte-compilation, so a new .eln file is produced when the *.el file is
newer than the corresponding .elc file, which causes Make to invoke
the byte+native-compilation.  But in a release tarball, all *.elc
files are newer than the corresponding *.el files, so this Make rule
will not be triggered, and the *.eln files will not be produced.  So
Emacs will be dumped with byte-compiled *.elc files, which is not what
we want, I think.

So unless I'm missing something, we need some Make wizardry to trigger
native-compilation at build time, even if the corresponding *.elc
files don't need to be re-generated.

Comments?