Support older versions of OpenSSL
Support older versions of OpenSSL

Summary:
Use getSelectedNextProtocolNoThrow instead of getSelectedNextProtocol so
that the handshake can complete with older versions of OpenSSL that do
not support protocol negotiation.
Closes https://github.com/facebook/wangle/pull/88

Reviewed By: knekritz

Differential Revision: D4702473

Pulled By: anirudhvr

fbshipit-source-id: 1fbab1dd6136aee08322f05382a3d0dc3ebf8079

facebook/wangle,facebook/wangle,facebook/wangle