[cogl] frame-info: add missing annotation

[Robert Bragg <rbragg src gnome org>]

commit 0882286ba127dd1f1c8088f9387bc4d7cab5daec
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Tue Sep 3 16:14:28 2013 +0100

    frame-info: add missing annotation
    
    Reviewed-by: Robert Bragg <robert linux intel com>
    
    (cherry picked from commit bd69f5963cb666aa929d510e915e90d8b0ea8f25)

 cogl/cogl-frame-info.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/cogl/cogl-frame-info.h b/cogl/cogl-frame-info.h
index 36f8a04..8d9c39b 100644
--- a/cogl/cogl-frame-info.h
+++ b/cogl/cogl-frame-info.h
@@ -116,8 +116,8 @@ float cogl_frame_info_get_refresh_rate (CoglFrameInfo *info);
  *
  * Gets the #CoglOutput that the swapped frame was presented to.
  *
- * Return value: The #CoglOutput that the frame was presented to, or
- *               %NULL if this could not be determined.
+ * Return value: (transfer none): The #CoglOutput that the frame was
+ *        presented to, or %NULL if this could not be determined.
  * Since: 1.14
  * Stability: unstable
  */