[map] Don't resize map if not necessary

src/hb-map.hh

@@ -160,6 +160,8 @@ struct hb_hashmap_t
   {
     if (unlikely (!successful)) return false;
 
+    if (new_population != 0 && new_population <= population) return true;
+
     unsigned int power = hb_bit_storage (hb_max (population, new_population) * 2 + 8);
     unsigned int new_size = 1u << power;
     item_t *new_items = (item_t *) hb_malloc ((size_t) new_size * sizeof (item_t));