818a504b94
When booted via isoboot(8) loader will be handed a disk that simply contains an ISO9660 image. Currently this confuses it greatly. Teach it how to spot that it's in this situation and that ISO9660 has one "partition" covering the whole disk. Reviewed by: imp Sponsored by: iXsystems, Inc. Differential Revision: https://reviews.freebsd.org/D14915