avidec: Reduce log level for out of index error message.

Its otherwise spaming every time one tries to seek to outside
the file.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avidec.c

@@ -1387,7 +1387,7 @@ static int avi_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp
     index= av_index_search_timestamp(st, timestamp * FFMAX(ast->sample_size, 1), flags);
     if (index<0) {
         if (st->nb_index_entries > 0)
-            av_log(s, AV_LOG_ERROR, "Failed to find timestamp %"PRId64 " in index %"PRId64 " .. %"PRId64 "\n",
+            av_log(s, AV_LOG_DEBUG, "Failed to find timestamp %"PRId64 " in index %"PRId64 " .. %"PRId64 "\n",
                    timestamp * FFMAX(ast->sample_size, 1),
                    st->index_entries[0].timestamp,
                    st->index_entries[st->nb_index_entries - 1].timestamp);