StimBuff: Make virtual so we can dynamic_cast in getOrCreateStimBuff

stimBuffApis/livoxGen1/pcloudStimulusProducer.h

@@ -67,6 +67,10 @@ public:
 			&deviceAttachmentSpec,
 		int histbuffMs) override;
 
+	std::shared_ptr<StimulusBuffer> getAttachedStimulusBuffer(
+		const std::shared_ptr<device::DeviceAttachmentSpec>& spec)
+		const override;
+
 protected:
 	void stimFrameProductionTimesliceInd() override;