wip/shunt 1.7.2 NetBSD

shunt was originally written for burning multi-set CDROM backups using mkiosfs and cdrecord. You can get both by downloading the latest cdrtools package. For burning DVDs, mkisofs (currently) has limitations on how much data it can stream while creating an ISO 9660 file system on the fly. Because of this, you need to replace mkisofs with flyisofs (which is part of the shunt source package that you can download below). Also, depending on your setup, you may have a forked or old version of cdrecord that cannot burn DVDs. If so, you probably will want to use growisofs instead.