stuff duplication by expressing it in terms of <bsd.files.mk>. Allow for
multiple inclusion of <bsd.files.mk> by clearing ${FILES} at the end, and
using FILES+= rather than FILES= in <bsd.info.mk>.
and the filesystem is full. Added ${RENAME} flag to install, which when set
to -r installs on a temporary file and then renames to the final destination.
${RENAME} is currently set to nothing in bsd.own.mk, but one can turn it
on in /etc/mk.conf.