message: Fix compilation warning
  ```
  onnx/defs/schema.cc:28:7: warning: field 'description_' will be initialized after field 'type_str_' [-Wreorder]
  description_(description),
  ^
  1 warning generated.
  ```
diff: @@ -25,8 +25,8 @@ OpSchema::FormalParameter::FormalParameter(
  const std::string& type_str,
  bool optional)
  : name_(name),
  - description_(description),
  type_str_(type_str),
  + description_(description),
  is_optional_(optional) {}
  const std::string& OpSchema::FormalParameter::GetName() const {
  