Heads up: moving some uvmexp stat to being per-cpu

[Matt Thomas <matt%3am-software.com@localhost>]

I have a fairly large but mostly simple patch which changes the stats collected 
in
uvmexp for faults, intrs, softs, syscalls, and traps from 32 bit to 64 bits and
puts them in cpu_data (in cpu_info).  This makes more accurate and a little 
cheaper
to update on 64bit systems.

I've had to modify some assembly from architectures I'm not really proficient at
(m68k, sparc, sparc64, sh3, i386, amd64) but I think did so correctly.  I would
appreciate some reviews of those changes.  I've verified that all kernels still
build (except those that didn't before the changes).

This change also remove the include of <uvm/uvm_extern.h> from files where it
isn't needed.

The diffs are at http://www.netbsd.org/uvmexp-diff.txt 

Have fun reading them!

I'll wait a few days for comments until I do the commit of this change.