x86 changes

[Andrew Doran <ad%netbsd.org@localhost>]

Hi,

I just realised that I am not subscribed to this list.. Is anyone willing to
try a Xen kernel with this patch?

        http://www.netbsd.org/~ad/x86.diff

Among other things, it:

- makes the i386 kernel compile with pcc (well almost, a number of files
  are problematic)
- reduces amd64 GENERIC.MP kernel by ~130kb, similar for the others I guess
- makes x86 bus_space and bus_dma more LKM friendly
- shares a few more files between the x86 ports

Thanks,
Andrew