Complete the dosparts -> mbrparts conversion. Only x86k new uses dosparts
because it also uses struct dos_partition.

branches: 1.3.2; 1.3.12;
Add getlabelusesmbr(), as proposed in
http://mail-index.netbsd.org/tech-userlevel/2011/08/25/msg005404.html
This is used by disk tools such as disklabel(8) to dynamically decide is
the undelyling platform uses a disklabel-in-mbr-partition or not
(instead of using a compile-time list of ports).
getlabelusesmbr() reads the sysctl kern.labelusesmbr, takes its value from the
machdep #define LABELUSESMBR.
For evbmips, make LABELUSESMBR 1 if the platform uses pmon
as bootloader, and 0 (the previous value) otherwise.

If cpu_disklabel includes struct dkbad, define __HAVE_DISKLABEL_DKBAD.
This allows use of subr_disk_mbr on all archs. Default to it for
the rump disk component. No functional change for regular kernels.
(The other option would've been to include dkbad in disklabels
everywhere, but arguably this approach has less possible side-effects,
especially given that wedges and related magic will take over the
world any second now).

branches: 1.1.2; 1.1.4; 1.1.6; 1.1.8; 1.1.18;
Import the rs6000 port into the tree.

This port of NetBSD is intended to run on MCA-based IBM RS/6000
machines. The port so far has only been tested on a 7006-41T, which is a
601-based RS/6000. The port also contains a limited set of code for the
7012-3XX machines, but support for those is a long way off still.

The port builds and generates a working kernel, however, it still lacks
bus_dma code for the MCA bus, so at present, only the com ports work,
though any other device (such as the printer/keyboard) located on the
ioplanar could probably be made to work. Work will continue on this port
as I iron out the DMA code.

This port was made possible by a generous gonation of hardware by Kevin
Bowling, who also provided much of the documentation for the port.