Adapt the mfsroot environment of sysinstall to the needs of the new dhclient.

This involves having passwd bits available so that seteuid("_dhcp") work,
and creating /var/empty so that chroot(_VAR_EMPTY) works.  My gut feeling
is that the better solution is to make privsep and chroot optional in
dhclient, but this works well for now and is low-risk.

Approved by: re

release/Makefile

@@ -698,7 +698,8 @@ release.8:
 	rm -rf ${RD}/mfsfd
 	mkdir ${RD}/mfsfd
 	cd ${RD}/mfsfd && \
-		mkdir -p etc/defaults dev mnt stand/etc/defaults stand/help
+		mkdir -p etc/defaults dev mnt stand/etc/defaults stand/help \
+		var/empty
 	@cd ${.CURDIR} && $(MAKE) installCRUNCH CRUNCH=boot \
 		DIR=${RD}/mfsfd/stand ZIP=false
 	( cd ${RD}/mfsfd && \
@@ -711,6 +712,8 @@ release.8:
 	    ${RD}/mfsfd/etc/defaults/pccard.conf
 .endif
 	cp ${.CURDIR}/../etc/usbd.conf ${RD}/mfsfd/etc/usbd.conf
+	cp ${.CURDIR}/../etc/master.passwd ${RD}/mfsfd/etc/master.passwd
+	pwd_mkdb -d ${RD}/mfsfd/etc -p ${RD}/mfsfd/etc/master.passwd
 	( for F in defaults/rc.conf netconfig protocols ; do \
 		sed -e '/^#.*$$/d' -e 's/[:space:]*#.*$$//g' \
 		${RD}/trees/base/etc/$$F > ${RD}/mfsfd/stand/etc/$$F ; \