Turn onnx functions into static (pytorch#147598)

To avoid exposing ONNX symbols.

Pull Request resolved: pytorch#147598
Approved by: https://github.com/justinchuby

Author: cyyever

torch/csrc/jit/serialization/export.cpp

@@ -414,7 +414,7 @@ class GraphEncoder {
   static constexpr size_t ParamSizeThresholdForExternalStorage = 1024;
 };
 
-onnx::TensorProto_DataType ATenTypeToOnnxType(at::ScalarType at_type) {
+static onnx::TensorProto_DataType ATenTypeToOnnxType(at::ScalarType at_type) {
   switch (at_type) {
     case at::kDouble:
       return onnx::TensorProto_DataType_DOUBLE;
@@ -459,7 +459,7 @@ onnx::TensorProto_DataType ATenTypeToOnnxType(at::ScalarType at_type) {
   }
 }
 
-onnx::AttributeProto_AttributeType ATenAttributeKindToOnnxAttributeType(
+static onnx::AttributeProto_AttributeType ATenAttributeKindToOnnxAttributeType(
     AttributeKind at_kind,
     const jit::Symbol name) {
   switch (at_kind) {