hls: Trying to work arround streams without bandwidth value.

A 0 bandwidth forbid us to seek, as the position would always be 0.
This fixes one of the problems described in #5370
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/stream_filter/httplive.c

@@ -1558,6 +1558,11 @@ static int hls_DownloadSegmentData(stream_t *s, hls_stream_t *hls, segment_t *se
         return VLC_EGENERIC;
     }
     mtime_t duration = mdate() - start;
+    if (hls->bandwidth == 0)
+    {
+        /* Try to estimate the bandwidth for this stream */
+        hls->bandwidth = (uint64_t)((double)segment->size / ((double)duration / 1000000.0));
+    }
 
     /* If the segment is encrypted, decode it */
     if (hls_DecodeSegmentData(s, hls, segment) != VLC_SUCCESS)