fill in sysdep_update_cpu_data from kstat

Watching the pretty bars and using them to visualize load across the machine is usually my primary reason for using htop, so I wanted to contribute this to your Solaris htop porting effort.

This is a patch to fill in sysdep_update_cpu_data using the kstat interface. The strategy (and some code) for doing this were gleaned from the implementation of Unix Top (www.unixtop.org), version 3.8beta1.