Fix --disable-ipv6 option

Commit 7e2129f ("ensure that openconnect_disable_{dtls,ipv6} do
nothing if vpninfo has ever been connected") added a check to disallow
setting this... if it wasn't already set, OR the connection had
previously been established. Which seems wrong; I think that was
supposed to have been *AND*.

Not that I object very much to this not working, a whole quarter of a
century after RFC1883 was published. But I wanted to use it for testing
PPP negotiation, and it wasn't working.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

library.c

@@ -626,8 +626,8 @@ int openconnect_disable_ipv6(struct openconnect_info *vpninfo)
 	 * unconfigured state. (Neither a closed TLS socket
 	 * nor tunnel socket is a reliable indicator.)
 	 */
-	if (!vpninfo->disable_ipv6
-	    || vpninfo->ssl_times.last_tx != 0)
+	if (!vpninfo->disable_ipv6 &&
+	    vpninfo->ssl_times.last_tx != 0)
 		return -EINVAL;
 	vpninfo->disable_ipv6 = 1;
 	return 0;