Hook up performance counters
We need to expose the OA counters via some mechanism.
This would likely involve:
- Exposing OA via the current Gallium batch query interface
- Possibly making st/mesa expose GL_INTEL_performance_query on top of the Gallium interface
The first step would get us OA via GL_AMD_performance_monitor.
If the Gallium interface doesn't suit our needs, we should modify or extend it.