ADB support - round 2

[Nathan Whitehorn]

I've fixed up the ADB support I emailed about a while ago a little bit. 
On CUDA machines, it works well, aside from keyboard autorepeat being 
slow, and arrow keys not working in X. The code also isn't style(9) 
compliant at all, and is missing copyright headers, etc.

This version now also has experimental PMU support, so the built-in 
keyboard and mouse in Apple laptops can work, if your machine doesn't 
kernel panic instantly, which is what happens frequently on my test G4 
iBook. It is also hard-coded to use IRQ 47 instead of finding it from 
the extint-gpio1 like it should.

The last is easy to change -- the first I cannot figure out at all. I'm 
hoping someone with better debugging skills than I can figure out what 
it going on there. It seems to be crashing in the interrupt handler, but 
somehow after pmu_intr() has exited, and my access to the machine in 
question is limited.

Anyway, the code: http://banshee.uchicago.edu/~nwhitehorn/adb.tgz
-Nathan