free private streamcontext when closing demuxer, fix memory leak, patch by Art...

free private streamcontext when closing demuxer, fix memory leak, patch by Art Clarke, aclarke at vlideshow dot com

Originally committed as revision 13800 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -1899,6 +1899,7 @@ static int mov_read_close(AVFormatContext *s)
         av_freep(&sc->drefs);
         if (sc->pb && sc->pb != s->pb)
             url_fclose(sc->pb);
+        av_freep(&sc);
     }
     if(mov->dv_demux){
         for(i=0; i<mov->dv_fctx->nb_streams; i++){