[ot] Apply langsys's required feature even if no other feature exists
diff --git a/src/hb-ot-map.cc b/src/hb-ot-map.cc
index 54b0ce3..b7cbafa 100644
--- a/src/hb-ot-map.cc
+++ b/src/hb-ot-map.cc
@@ -164,9 +164,6 @@
 						&required_feature_tag[table_index]);
   }
 
-  if (!feature_infos.len)
-    return;
-
   /* Sort features and merge duplicates */
   {
     feature_infos.qsort ();