OClCollMeshEng: Use RAII for unmapBuffer() event destruction

stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h

@@ -40,11 +40,19 @@ struct ClKernelDeleter
 		{ if (kernel) { clReleaseKernel(kernel); } }
 };
 
+struct ClEventDeleter
+{
+	void operator()(cl_event event) const
+		{ if (event) { clReleaseEvent(event); } }
+};
+
 // Type aliases for OpenCL handle unique_ptrs
 using ClProgramPtr = std::unique_ptr<
 	std::remove_pointer_t<cl_program>, ClProgramDeleter>;
 using ClKernelPtr = std::unique_ptr<
 	std::remove_pointer_t<cl_kernel>, ClKernelDeleter>;
+using ClEventPtr = std::unique_ptr<
+	std::remove_pointer_t<cl_event>, ClEventDeleter>;
 
 class PcloudStimulusProducer;