tun: Don't call tunnel script on reconnect events

If --script-tun is used, the vpnc_script is not invoked for pre-init,
connect, or disconnect events.  However, it is invoked on reconnect, and
this may confuse the tunnel script.

Add an extra check to script_config_tun() to make the reconnect behavior
consistent with the behavior of other events.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

tun.c

@@ -376,7 +376,7 @@ int script_config_tun(struct openconnect_info *vpninfo, const char *reason)
 {
 	int ret;
 
-	if (!vpninfo->vpnc_script)
+	if (!vpninfo->vpnc_script || vpninfo->script_tun)
 		return 0;
 
 	setenv("reason", reason, 1);