Eat scroll event if a key binding function is executed because of it.

When an axis (scroll) event results in a key binding function
being executed, eat the scroll event so the underlying window
doesn't receive it.
Thanks to Scott Moreau for helping me solve this.
diff --git a/src/compositor.c b/src/compositor.c
index eeb57f9..6ea8af5 100644
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -1859,10 +1859,11 @@
 
 	weston_compositor_wake(compositor);
 
-	if (value)
-		weston_compositor_run_axis_binding(compositor, seat,
-						   time, axis, value);
-	else
+	if (!value)
+		return;
+
+	if (weston_compositor_run_axis_binding(compositor, seat,
+						   time, axis, value))
 		return;
 
 	if (pointer->focus_resource)