release(7): Enable zpoolupgrade rc script in ZFS based VM images

This will enable VM access to all ZFS feature automatically, only on a
newly installed or provisioned VM or cloud instance.

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D37283

release/tools/vmimage.subr

@@ -83,6 +83,7 @@ vm_install_base() {
 	if [ "${VMFS}" = zfs ]; then
 		echo "zfs_enable=\"YES\"" >> ${DESTDIR}/etc/rc.conf
 		echo "zpool_reguid=\"zroot\"" >> ${DESTDIR}/etc/rc.conf
+		echo "zpool_upgrade=\"zroot\"" >> ${DESTDIR}/etc/rc.conf
 	fi
 
 	if ! [ -z "${QEMUSTATIC}" ]; then