Currently the trace tool tracks an overall counts of goroutine states,
but not the states of any individual goroutine. We're about to add
more sophisticated blocked-state tracking, so add this tracking and
base the state counts off the tracked goroutine states.

Change-Id: I943ed61782436cf9540f4ee26c5561715c5b4a1d
Reviewed-on: https://go-review.googlesource.com/30703
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>