${RELEASEDIR}/${MACHINE}. The former is the blessed way as it's
defined as a "subdirectory used below ${RELEASEDIR} when building a
release" and defaults to MACHINE in bsd.own.mk.
Make sure that ${RELEASEDIR}/${RELEASEMACHINEDIR} exists before
installing notes in to it. It only ever worked because ~all ports
build at least one kernel as part of make release, and so the release
directory was created when kernel sets are installed.
XXX: Why don't we create ${RELEASEDIR}/${RELEASEMACHINEDIR} from the
top-level makefile before running make release?
4402b3f15c