message: dnn(ocl4dnn): calculate activation expression once
  to avoid multiple conditional calls via sub_group() functions
diff: #endif
  #ifdef FUSED_CONV_ELTWISE
  -#define ACTIVATION_FUNCTION(_dst_, _offset_, _data_, _channel_) do { (_dst_)[(_offset_)] = ACTIVATION_RELU_FUNCTION(eltwise_data[(_offset_)] + (_data_), _channel_);} while(0)
  +#define ACTIVATION_FUNCTION(_dst_, _offset_, _data_, _channel_) do { \
  + const Dtype _x_ = eltwise_data[(_offset_)] + (_data_); \
  + (_dst_)[(_offset_)] = ACTIVATION_RELU_FUNCTION(_x_, _channel_); \
  +} while(0)
  #define ELTWISE_DATA_ARG __global Dtype* eltwise_data,
  #else
  -#define ACTIVATION_FUNCTION(_dst_, _offset_, _data_, _channel_) do { (_dst_)[(_offset_)] = ACTIVATION_RELU_FUNCTION(_data_, _channel_);} while(0)
  +#define ACTIVATION_FUNCTION(_dst_, _offset_, _data_, _channel_) do { \
  + const Dtype _x_ = (_data_); \
  + (_dst_)[(_offset_)] = ACTIVATION_RELU_FUNCTION(_x_, _channel_); \
  +} while(0)
  #define ELTWISE_DATA_ARG
  #endif
  