const internal/trace/tracev2.NumExperiments

2 uses

	internal/trace/tracev2 (current package)
		events.go#L106: 	NumExperiments

	runtime
		traceruntime.go#L29: 	buf           [2][tracev2.NumExperiments]*traceBuf // Per-M traceBuf for writing. Indexed by trace.gen%2.