lavc/h264dec: Improve "Increasing reorder buffer" message loglevel.

Do not show the message for the first frame by default, show a
warning if increasing is necessary in the middle of the stream.

libavcodec/h264dec.c

@@ -528,7 +528,8 @@ static void decode_postinit(H264Context *h, int setup_finished)
         h->last_pocs[0] = cur->poc;
         cur->mmco_reset = 1;
     } else if(h->avctx->has_b_frames < out_of_order && !sps->bitstream_restriction_flag){
-        av_log(h->avctx, AV_LOG_INFO, "Increasing reorder buffer to %d\n", out_of_order);
+        int loglevel = h->avctx->frame_number > 1 ? AV_LOG_WARNING : AV_LOG_VERBOSE;
+        av_log(h->avctx, loglevel, "Increasing reorder buffer to %d\n", out_of_order);
         h->avctx->has_b_frames = out_of_order;
     }