[clutter/clutter-1.22] docs: Add ClutterConstraintClass.update_preferred_size()

[Emmanuele Bassi <ebassi src gnome org>]

commit 1fe391606dff6f50eb74cf2ec8219f1a14a27695
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Dec 16 00:38:27 2014 +0000

    docs: Add ClutterConstraintClass.update_preferred_size()

 clutter/clutter-constraint.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/clutter/clutter-constraint.h b/clutter/clutter-constraint.h
index 485fe2c..ccd20cb 100644
--- a/clutter/clutter-constraint.h
+++ b/clutter/clutter-constraint.h
@@ -60,6 +60,9 @@ struct _ClutterConstraint
  * ClutterConstraintClass:
  * @update_allocation: virtual function used to update the allocation
  *   of the #ClutterActor using the #ClutterConstraint
+ * @update_preferred_size: virtual function used to update the preferred
+ *   size of the #ClutterActor using the #ClutterConstraint; optional,
+ *   since 1.22
  *
  * The #ClutterConstraintClass structure contains
  * only private data