[pcp] suitability of PCP for event tracing

[Ken McDonell]

It has taken me a while to work through all of the issues here, not to
mention more distractions than you could hit with a big stick.

Anyway putting an array of event records inside a pmResult is not going
to be too hard - see http://oss.sgi.com/~kenj/event-params.html

Pushing client context through PMCD to PMDAs is a much more challenging
task - see http://oss.sgi.com/~kenj/per-client-ctx.html for a proposal
and discussion.

Lemme know if this sounds good, bad or too ugly to contemplate ... I'll
start the implementation as soon as we seem to be approaching some sort
of consensus.

Cheers.