Fix export macros (pytorch#15856)

Summary:
Pull Request resolved: pytorch#15856

They seem to be wrong.
cc zdevito to take a look but I think this is now more correct.

It's weird this didn't cause linker errors. Probably, this functionality isn't used across library boundaries yet.

Reviewed By: dzhulgakov

Differential Revision: D13605257

fbshipit-source-id: 7077ca9027c3ac79a4847ec15ead7ddb28696445

aten/src/ATen/core/ivalue.h

@@ -39,7 +39,7 @@ struct CAFFE2_API ConstantString final : c10::intrusive_ptr_target {
 };
 
 template <typename Elem>
-struct C10_EXPORT List : c10::intrusive_ptr_target {
+struct CAFFE2_API List : c10::intrusive_ptr_target {
  private:
   std::vector<Elem> elements_;
 
@@ -67,7 +67,7 @@ struct C10_EXPORT List : c10::intrusive_ptr_target {
 
 struct Future;
 
-struct C10_EXPORT Tuple : public List<IValue> {
+struct CAFFE2_API Tuple : public List<IValue> {
   using List<IValue>::List;
   static c10::intrusive_ptr<Tuple> create(std::vector<IValue> elements_) {
     return c10::make_intrusive<Tuple>(std::move(elements_));