Added 'Extended Stream Properties' in asf muxer for WMV3 too.

It closes #3522.
(cherry picked from commit 7c801152)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/mux/asf.c

@@ -539,6 +539,7 @@ static int AddStream( sout_mux_t *p_mux, sout_input_t *p_input )
             {
                 tk->psz_name = "Windows Media Video 9";
                 tk->i_fourcc = VLC_FOURCC( 'W', 'M', 'V', '3' );
+                tk->b_extended = true;
             }
             else if( p_input->p_fmt->i_codec == VLC_CODEC_VC1 )
             {