New powerpc64 snapshot

[Nathan Whitehorn]

I have built a new powerpc64 snapshot that should have a more
functional installer and not have disk-detection problems on some
models of G5 Powermac. This snapshot can be found at
http://people.freebsd.org/~nwhitehorn/FreeBSD-9.0-20100910-SNAP-powerpc64

Installation directions are the same as for 32-bit PowerPC:
http://people.freebsd.org/~nwhitehorn/ppcinstall.txt

SMP is also now in the default powerpc64 kernel configuration, thanks
to Peter Grehan.
-Nathan