SSL: moved c->ssl->handshaked check in server name callback. Server name callback is always called by OpenSSL, even if server_name extension is not present in ClientHello. As such, checking c->ssl->handshaked before the SSL_get_servername() result should help to more effectively prevent renegotiation in OpenSSL 1.1.0 - 1.1.0g, where neither SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS nor SSL_OP_NO_RENEGOTIATION is available.