Summary: Which means `.native()` returns a `wstring`, and `.c_str()` returns a `wchar_t*`. As we're using them in places expecting a `char*`, convert to `string` first.

Reviewed By: yfeldblum

Differential Revision: D3506911

fbshipit-source-id: ca34b9888f98106914438490bbd860f9b922ad5e