use proper url_is_streamed() API

instead of messing with ByteIOContext internal is_streamed field

Originally committed as revision 11276 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/oggdec.c

@@ -438,7 +438,7 @@ ogg_get_length (AVFormatContext * s)
     int idx = -1, i;
     offset_t size, end;
 
-    if(s->pb->is_streamed)
+    if(url_is_streamed(s->pb))
         return 0;
 
 // already set

libavformat/utils.c

@@ -1603,7 +1603,7 @@ static void av_estimate_timings(AVFormatContext *ic, offset_t old_offset)
 
     if ((!strcmp(ic->iformat->name, "mpeg") ||
          !strcmp(ic->iformat->name, "mpegts")) &&
-        file_size && !ic->pb->is_streamed) {
+        file_size && !url_is_streamed(ic->pb)) {
         /* get accurate estimate from the PTSes */
         av_estimate_timings_from_pts(ic, old_offset);
     } else if (av_has_duration(ic)) {