util: Get rid of conditional compilation in calls_find_in_store()

This is not needed anymore after bumping the required glib version to 2.64.

src/util.c

@@ -180,15 +180,16 @@ calls_find_in_store (GListModel *list,
                      gpointer    item,
                      guint      *position)
 {
-#if GLIB_CHECK_VERSION(2, 64, 0)
+  GListStore *store = (GListStore *) list;
-  return g_list_store_find ((GListStore *) list,
-                            item,
-                            position);
-#else
   guint count;
 
   g_return_val_if_fail (G_IS_LIST_MODEL (list), FALSE);
 
+  if (G_IS_LIST_STORE (store))
+    return g_list_store_find (store,
+                              item,
+                              position);
+
   count = g_list_model_get_n_items (list);
 
   for (guint i = 0; i < count; i++) {
@@ -203,7 +204,6 @@ calls_find_in_store (GListModel *list,
     }
   }
   return FALSE;
-#endif
 }
 
 /**