Merged process-state-key-error [r=jseutter,ack] [f=1062278].
Handle new process states in when getting process information.
The bug report was about "t (tracing stop)", but a bunch of other states
can occur as well that we don't handle. I've change the code to use the
one-character representation of the process state that the kernel uses,
instead of using our own mapping. This ensure that future state
additions will be handled as well. As a result, we now represent the
"tracing stop" state as "t" instead of "I", but as far as I can see, the
only state we're explicitly checking for in our code is Z, so that
change shouldn't cause a problem.
I put in a special-case for "T (tracing stop)", since in Lucid you can
have both "T (stopped)" and "T (tracing stop)". I made it so that the
latter is represented by "t", since that's the way it is in releases
newer than Lucid.