avdevice/jack: use av_err2str to simplify code

No need to explicitly specify the buffer here as it is only
ever passed to av_log, so av_err2str can be used.

libavdevice/jack.c

@@ -291,11 +291,9 @@ static int audio_read_packet(AVFormatContext *context, AVPacket *pkt)
             av_log(context, AV_LOG_ERROR,
                    "Input error: timed out when waiting for JACK process callback output\n");
         } else {
-            char errbuf[128];
             int ret = AVERROR(errno);
-            av_strerror(ret, errbuf, sizeof(errbuf));
             av_log(context, AV_LOG_ERROR, "Error while waiting for audio packet: %s\n",
-                   errbuf);
+                   av_err2str(ret));
         }
         if (!self->client)
             av_log(context, AV_LOG_ERROR, "Input error: JACK server is gone\n");