avcodec/pngdec: print the actual number of bytes left in the error case

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/pngdec.c

@@ -559,7 +559,7 @@ static int decode_frame(AVCodecContext *avctx,
     }
     for (;;) {
         if (bytestream2_get_bytes_left(&s->gb) <= 0) {
-            av_log(avctx, AV_LOG_ERROR, "No bytes left\n");
+            av_log(avctx, AV_LOG_ERROR, "%d bytes left\n", bytestream2_get_bytes_left(&s->gb));
             if (   s->state & PNG_ALLIMAGE
                 && avctx->strict_std_compliance <= FF_COMPLIANCE_NORMAL)
                 goto exit_loop;