I've been rewhacking, somewhat gratuitously, the cpu switch stuff.

The basic intent is to try and lay a more explicit framework that
each specific alpha platform should have a file in <....alpha/alpha>
that can have explicit hooks not only for configuration but for
machine check operations, etc..

There'll be a number files touched and I can't test on all platforms
if I broke something and I plan to integrate later today if nobody screams.

-matt