Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix compilation errors.

I wonder how I managed to cross-compile this yesterday.

Update libdisk to use the explicing encoding function for sunlabel data
structures.

Fixed style(9)

Write the boot block to the first 16 sectors of all partitions, instead of
always to the first 16 sectors of the disk. The firmware reads the boot
code from a partition, defaulting to 'a' if none is specified, which only
corresponds to the first 16 sectors of the disk if 'a' is first. Solaris
often makes the swap partition first, instead of the root partition, and
users expect to be able to do the same with freebsd as well. This also
allows one to temporarily boot from another partition if the boot block
on the root partition gets scrambled somehow.

Fill in partition 2 with with "whole disk" parameters.

Actually save the bootblock in the disk structure. Write the bootblock
to the right place on the disk instead of srewn all over it.

Write out 15 sectors of boot code.

Add the write_spar64_disk.c to make life easier for testers.

This file depends on some major surgery in the rest of libdisk which is
not yet committed.