add evhtp_connection_ssl_new_dns

[ikonopistsev]

example

    const char* hostname = "www.gentoo.org";
    
    evhtp_connection_t* conn =
        evhtp_connection_ssl_new_dns(queue, dns, hostname, 443, ssl);

    // setup tls hos tname
    SSL_set_tlsext_host_name(conn->ssl, hostname);

    evhtp_request_t* req = evhtp_request_new(evhtp_callback, NULL);

    evhtp_headers_add_header(req->headers_out,
        evhtp_header_new("Host", hostname, NULL, NULL));

    evhtp_headers_add_header(req->headers_out,
            evhtp_header_new("Connection", "close", NULL, NULL));

    evhtp_make_request(conn, req, htp_method_GET, "/");