SSL: fixed SSL_clear_options() usage with OpenSSL 1.1.0+. In OpenSSL 1.1.0 the SSL_CTRL_CLEAR_OPTIONS macro was removed, so conditional compilation test on it results in SSL_clear_options() and SSL_CTX_clear_options() not being used. Notably, this caused "ssl_prefer_server_ciphers off" to not work in SNI-based virtual servers if server preference was switched on in the default server. It looks like the only possible fix is to test OPENSSL_VERSION_NUMBER explicitly.