Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.Approved by: re (implicit)Sponsored by: The FreeBSD Foundation
Add support for memory disk (md). The size of the memory diskis determined by MD_IMAGE_SIZE. A file system can be embeddedinto the loader with /sys/tools/embed_mfs.sh.Note that md.c is not included when MD_IMAGE_SIZE is not set.