CPU and GPU zone inconsistency

[erieaton-amd]

In the code, there seem to be a lot of similarity between CPU and GPU zones, except they use separate code paths. But GPU zones are more limited, you can't bring up a statistics window for them like you can with CPU zones. Do you think it would be feasible to unify the zone types code more to reduce duplication and ensure a consistent feature set?

[wolfpld]

Unification is not really an option, as that would waste the memory. Consider the cost of enlarging the ZoneEvent struct just by one byte when there's a billion zones in the trace.

[erieaton-amd]

Would it work to extend ZoneExtra instead?