avconv: drop additional strerror fallback

strerror_r is called by av_strerror already.

avconv.c

@@ -1757,10 +1757,11 @@ static int transcode_init(void)
         oc->interrupt_callback = int_cb;
         if ((ret = avformat_write_header(oc, &output_files[i]->opts)) < 0) {
             char errbuf[128];
-            const char *errbuf_ptr = errbuf;
+            av_strerror(ret, errbuf, sizeof(errbuf));
-            if (av_strerror(ret, errbuf, sizeof(errbuf)) < 0)
+            snprintf(error, sizeof(error),
-                errbuf_ptr = strerror(AVUNERROR(ret));
+                     "Could not write header for output file #%d "
-            snprintf(error, sizeof(error), "Could not write header for output file #%d (incorrect codec parameters ?): %s", i, errbuf_ptr);
+                     "(incorrect codec parameters ?): %s",
+                     i, errbuf);
             ret = AVERROR(EINVAL);
             goto dump_format;
         }