smp g5 testing!

hi!

i have attached a trashpanda style diff to
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=271826 ; if you have
a dual or quad g5 then please test it out and report back.

I have /just/ this diff in my tree and my dual cpu g5 is
booting/building world right now with two CPUs.

I have other issues to chase down on the g5 (notably why things don't
work right when I boot a non-debug kernel) but those can wait a little
bit.

Thanks!


-a