- factor out disksubr.c between sun3, sparc and sparc64. Keep the sun3
groveling code to find a NetBSD disklabel in the first sector (so that it
can find a label at the old sun3 LABELOFFSET) as a fallback is not
label at LABELOFFSET, or sun label is present.
- Fix the sun3 LABELOFFSET (was 64, but the kernel wrote the NetBSD label at
128)
- Make next68k disksubr.c always write a next-compatible disklabel.
- remove #ifdef __sparc__ hack from disklabel(8), and change it to issue
a DIOCWDINFO after writing the disklabel to the raw partition in the
-r/-I case (so that the kernel can convert the label if needed).