Use OpenCL 2.x API in GPU package when supported

  inline void push_command_queue() {

    cl_int errorv;

    _cq.push_back(cl_command_queue());

    _cq.back()=clCreateCommandQueue(_context,_cl_device,

                                    CL_QUEUE_PROFILING_ENABLE,&errorv);

#ifdef CL_VERSION_2_0

    cl_queue_properties props[] = {CL_QUEUE_PROPERTIES, CL_QUEUE_PROFILING_ENABLE, 0};

    _cq.back()=clCreateCommandQueueWithProperties(_context, _cl_device, props, &errorv);

#else

    _cq.back()=clCreateCommandQueue(_context, _cl_device, CL_QUEUE_PROFILING_ENABLE, &errorv);

#endif

    if (errorv!=CL_SUCCESS) {

      std::cerr << "Could not create command queue on device: " << name()

                << std::endl;