[bindings] Fix ownership of returned hb_language_t

It should not be freed by the caller.
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index b9fe263..eecb9d0 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -967,7 +967,7 @@
  *
  * 
  *
- * Return value: 
+ * Return value: (transfer none):
  *
  * Since: 1.0
  **/
diff --git a/src/hb-common.cc b/src/hb-common.cc
index c0233f3..ac10cf2 100644
--- a/src/hb-common.cc
+++ b/src/hb-common.cc
@@ -286,7 +286,7 @@
  *
  * 
  *
- * Return value: 
+ * Return value: (transfer none):
  *
  * Since: 1.0
  **/