matroskamux: Clip maximum cluster duration to the maximum possible value

Only up to timescale * G_MAXINT16 is possible as cluster duration, which
is already higher than our default value. Using higher values would
cause overflows and broken files.

Based on the investigation by Nicola Murino <nicola.murino@gmail.com>

https://bugzilla.gnome.org/show_bug.cgi?id=792775
diff --git a/gst/matroska/matroska-mux.c b/gst/matroska/matroska-mux.c
index 0a05ba2..78cffe8 100644
--- a/gst/matroska/matroska-mux.c
+++ b/gst/matroska/matroska-mux.c
@@ -3725,7 +3725,8 @@
           mux->min_cluster_duration));
   is_max_duration_exceeded = (mux->max_cluster_duration > 0
       && buffer_timestamp > mux->cluster_time
-      && (buffer_timestamp - mux->cluster_time) >= mux->max_cluster_duration);
+      && (buffer_timestamp - mux->cluster_time) >=
+      MIN (G_MAXINT16 * mux->time_scale, mux->max_cluster_duration));
 
   if (mux->cluster) {
     /* start a new cluster at every keyframe, at every GstForceKeyUnit event,