[libchamplain] Fix warning

[Jiří Techet <jiritechet src gnome org>]

commit eb2cff0f429ad542d7eba55232c33579e5cceddd
Author: Jiří Techet <techet gmail com>
Date:   Wed Mar 18 10:49:58 2015 +0100

    Fix warning

 champlain/champlain-view.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/champlain/champlain-view.c b/champlain/champlain-view.c
index d72b4dd..6ad4b4e 100644
--- a/champlain/champlain-view.c
+++ b/champlain/champlain-view.c
@@ -390,7 +390,7 @@ scroll_event (G_GNUC_UNUSED ClutterActor *actor,
     {
       gdouble dx, dy;
 
-      clutter_event_get_scroll_delta (event, &dx, &dy);
+      clutter_event_get_scroll_delta ((ClutterEvent *)event, &dx, &dy);
 
       /* Use a threshhold value to avoid jitter */
       if (fabs(dy) < 0.75)