KEXEC works on ALPHA!

[Eric W. Biederman]

I can boot linux from linux on the ALPHA.

Still todo is getting out all of the booting & rebooting
glitches, and generally cleaning up the interface.  But
since I have working code to start with it should be much easier.

I have one nasty hack to get around what appears to be a SRM bug.
And for some really weird reason linux doesn't save the boot
page table the second time it boots. So kexec only works once ;(

So there is still work to do before I call it done, but it works
now!

Eric