amd64 world compiles (again!)

[Matthew Dillon]

    Looking at the current platform/pc32 I see a few things that 
    could probably be moved to something like platform/pccommon,
    but not tons of stuff.  apm, acpica5, and a few files in
    platform/pc32/i386 like est.c could be moved.  Almost nothing else.
    Things like, say, isa/clock.c might look portable at the outset
    but are probably best left separate.  Similarly, files like isa/npx.c
    have a ton of compatibility code for older cpus that do not apply to
    64 bit mode operation and we would want to be able to optimize it for
    64 bit builds without messing with the compatibility for 32 bit builds.
    A lot of the files are like that.

    We only have 2MB of source in platform/pc32.

						-Matt