Could this be brought into emacs.mk so it happens automatically for any packages that happen to produce .elc as part of their build?

I think there were only about 10 of the 100ish ports that I gave up trying to mess with the upstream build to prevent .elc installation. We could put something in emacs.mk, but it would have to be blunt and start the search at ${STAGEDIR}${PREFIX}/${EMACS_SITE_LISPDIR}/ because each port might put .elc files in different subdirectories. I think it would be better to fix the builds of these 10 ports, but that's a refinement I'll tackle a bit later.