e - avoid segv's when zero screens are configured

at least backlight won't be applied now...

src/bin/e_backlight.c

@@ -261,6 +261,7 @@ _backlight_devices_device_zone_get(Backlight_Device *bd)
    snprintf(buf, sizeof(buf), "%s/%s", bd->output? bd->output: "", bd->edid ? bd->edid : "");
    EINA_LIST_FOREACH(e_comp->zones, l, zone)
      {
+        if (!zone->randr2_id) continue;
         if (!strcmp(zone->randr2_id, buf)) return zone;
      }
    return NULL;

src/bin/e_randr2.c

@@ -1493,6 +1493,7 @@ e_randr2_screen_id_find(const char *id)
    Eina_List *l;
    E_Randr2_Screen *s;
 
+   if (!id) return NULL;
    EINA_LIST_FOREACH(e_randr2->screens, l, s)
      {
         if (!strcmp(id, s->id)) return s;