[9fans] usb/disk install for amd64

[erik quanstrom <quanstro@quanstro.net>]

/n/atom/ftp/usbinstamd64.bz2 (http://ftp.9atom.org/other/usbinstamd64.bz2)
is an image suitable for installing 9atom with an
amd64 kernel and executables from a usb stick or
directly from a hard drive.  this is much like the
usbtest image, but with full source and docs.

i am currently using the test version to work on a mac pro
that doesn't seem to want to talk to its onboard ethernet.
(no doubt, this is my fault.)

since this is a very first draft, the new installer can be run
directly from /sys/lib/dist/amd64/install/main.  this will
be cleaned up soon.

it's not entirely clear that a new installer was the best idea,
but if you want to install amd64, please give it a try.  now's
the time to complain.  :-)

the new installer has a few assumptions that may or may
not be an improvement.  here's a haphazard, and incomplete
list:

1.  executables are rebuilt locally to make the image as small
as possible.

2.  the existing image is to be paved.  i've had a lot of trouble
with bad installs "sticking around".  perhaps i'm unique.  i'd
like some feedback on this.

3.  the installed image is assumed to be stepping stone to a
proper install of plan 9.  so kfs, as the simplist file system,
was used.  (it may be advantagous to use cwfs in the future
for this because the image, dropped in a larger partition can
automaticly resize to fit.)  this is just a shim.

Mkfsboot (see mkfsconf(8)) will build a ken file server boot
image for a proper file server.  Mkcpuboot(8) will build a
self-booting file server that takes its root from the network.
standalone scripts for building fossil(+venti), and an auth
server are planned.

- erik