Ignore password validation is pam is in wrong state

Long description:

This add a protection against wrong password spamming

To apply this patch, use:
curl http://cr.i3wm.org/patch/655/raw.patch | git am

@@ -299,6 +299,9 @@ static void handle_key_press(xcb_key_press_event_t *event) {

     case XKB_KEY_Return:

     case XKB_KEY_KP_Enter:

     case XKB_KEY_XF86ScreenSaver:

+        if (pam_state == STATE_PAM_WRONG)

+            return;

+

         if (skip_without_validation()) {

             clear_input();

             return;