SSL: set TCP_NODELAY on SSL connections before handshake. With OpenSSL 1.1.0+, the workaround for handshake buffer size as introduced in a720f0b0e083 (ticket #413) no longer works, as OpenSSL no longer exposes handshake buffers, see https://github.com/openssl/openssl/commit/2e7dc7cd688. Moreover, it is no longer possible to adjust handshake buffers at all now. To avoid additional RTT if handshake uses more than 4k we now set TCP_NODELAY on SSL connections before handshake. While this still results in sub-optimal network utilization due to incomplete packets being sent, it seems to be better than nothing.