reduction all axes export fix

Source/CNTKv2LibraryDll/proto/onnx/CNTKToONNX.cpp

@@ -3464,11 +3464,19 @@ void CNTKToONNXHelper::CopyAttributes(const FunctionPtr& src, LotusIR::Node* nod
                 Axis axis = (Axis)(src->Attributes()[L"axis"].Value<Axis>());
                 // Reduction on batch axis in CNTK removes the batch axis, even if keepdims is true. 
                 // For ONNX export we need to make sure we export keepdims as 0 (false). 
-                if (axis == Axis::DefaultBatchAxis())
+                // The same applies for All axes 
+                if (axis == Axis::DefaultBatchAxis() || axis == Axis::AllAxes() || axis == Axis::AllStaticAxes())
                     keepReducedDimensions = 0;
-                int64_t ax = ConvertAxisToOnnx(axis, src->Inputs()[0]);
-
-                node->AddAttribute("axis", ax);
+                if (node->OpType() != "ArgMax" && node->OpType() != "ArgMin")
+                {
+                    std::vector<int64_t> axes = ConvertAxesToOnnx(std::vector<Axis>({ axis }), src->Inputs()[0]);
+                    node->AddAttribute("axes", axes);
+                }
+                else
+                {
+                    int64_t ax = ConvertAxisToOnnx(axis, src->Inputs()[0]);
+                    node->AddAttribute("axis", ax);
+                }
             } 
 
             node->AddAttribute("keepdims", keepReducedDimensions);