fakevideosink: explicit type cast for max-lateness property setter

g_object_set() expects the parameters values to be the exact type of the
property being set.
diff --git a/gst/debugutils/gstfakevideosink.c b/gst/debugutils/gstfakevideosink.c
index 4b98dfa..0ebec64 100644
--- a/gst/debugutils/gstfakevideosink.c
+++ b/gst/debugutils/gstfakevideosink.c
@@ -179,8 +179,8 @@
     GstPad *ghost_pad;
 
     /* mimic GstVideoSink base class */
-    g_object_set (child, "max-lateness", 20000000, "qos", TRUE, "sync", TRUE,
-        NULL);
+    g_object_set (child, "max-lateness", G_GINT64_CONSTANT (20000000), "qos",
+        TRUE, "sync", TRUE, NULL);
 
     gst_bin_add (GST_BIN (self), child);