This is based on the newfs(8) command for ffs, but
most ext2fs specific part is written from scratch.
Tested on alpha, cobalt, i386 and sgimips with some disks and vnd(4),
and at least cobalt's firmware can load boot files from an ext2fs
E2FS_REV0 partition created by this native newfs_ext2fs(8) command.
Closes PR bin/16175.
tsutsui