This reveals that we've got really bogus times from these events. I
think there are two things here: the begin is the submit time, not the
submit-to-hardware time. And the end time is retire, which is too
delayed to be really useful. We need to move i915 over to the
low-level tracepoints.
However, this code proved to be useful for vc4, where I have good
timings.
The goal here is to avoid having to hard code what visualizers are shown
from the .ui files. We just should add things that we find are supported.
Long term, I think we'll add a concept of an "instrument" which is the
combination of a data source (SpSource) and a visualizer (SpVisualizerRow).
The other goal here is to enable the future support for discovering marks
and adding rows for each of those threads.
The lib/ directory was getting a bit out of hand, so this tries
to organize things a bit so it is easier going forward to locate
the code people want to patch.
