Summary:
[Folly] `throw_exception` to support `-fno-exceptions`, switching all invocations of `std::__throw_....`.

Removes the need to use the non-portable `bits/functexcept.h`.

Reviewed By: mzlee, ot

Differential Revision: D7050335

fbshipit-source-id: 53d15639baa268a51f703816f04f314454d64979