[boost] [Asio][ssl] develop broken

After the changes today (introduced in https://github.com/boostorg/asio/commit/0568d3bf0b492887c6c48d05f5492a782daf... ) an overload of async_handshake( https://github.com/boostorg/asio/blob/develop/include/boost/asio/ssl/stream....) fails to compile because of the signature mismatch in async_result. This is a show-stopper, because it breaks quite a bit of code in Beast.