message: Clarify why we aren't using setPrePadding/setPostPadding for conv
diff: @@ -1978,11 +1978,12 @@ Status ConvertConv2DHelper(OpConverterParams* params, int group,
  padding = {{0, 0}, {0, 0}};
  }
  - // TensorRT 5.1 added support for asymmetric padding. Due to a bug in 5.1.2,
  - // we can only use asymmetric padding in convolutions with 5.1.3+.
  + // Handle asymmetric padding. TensorRT 5.1 added support for asymmetric
  + // padding via setPrePadding and setPostPadding. Due to a bug in 5.1.2, we can
  + // only use asymmetric padding in convolutions with 5.1.3+. But in 5.1.3, we
  + // will always use setPaddingMode for simplicity.
  if (padding[0].first != padding[0].second ||
  padding[1].first != padding[1].second) {
  - // Handle asymmetric padding.
  auto pad_layer = params->converter->network()->addPadding(
  *tensor, nvinfer1::DimsHW(padding[0].first, padding[1].first),
  nvinfer1::DimsHW(padding[0].second, padding[1].second));
  @@ -2804,7 +2805,6 @@ Status ConvertPool(OpConverterParams* params) {
  layer->getOutput(0));
  layer->setStride(stride);
  -// TensorRT 5.1.3 added support for padding modes.
  #if IS_TRT_VERSION_GE(5, 1, 3, 0)
  // VALID padding is the default TRT behavior.
  if (attrs.get<string>("padding") == "SAME") {
  