Summary:
So far infer had very fragile mechanism to detect smart pointers. It was looking for "std" and "(shared|unique)_ptr" inside name string.
This is easy to trick (like mystd::shared_ptr) and not something we want.
Instead, inside models create models inside infer_std_model namespace. Then just "export" that model into std namespace
via `using shared_ptr = infer_std_model<T>;`
Reviewed By: jvillard
Differential Revision: D3703827
fbshipit-source-id: 9640fc2