baseparse: estimate duration on EOS

For files which are smaller than 1.5 seconds, the duration
estimation does not happen. So the duration will always be
displayed as 0. Updating the duration on EOS when the estimation
has not happened already

https://bugzilla.gnome.org/show_bug.cgi?id=750131

libs/gst/base/gstbaseparse.c

@@ -3396,6 +3396,9 @@ pause:
       push_eos = TRUE;
     }
     if (push_eos) {
+      if (parse->priv->estimated_duration <= 0) {
+        gst_base_parse_update_duration (parse);
+      }
       /* Push pending events, including SEGMENT events */
       gst_base_parse_push_pending_events (parse);