ffmpeg: Replace goto redo on decode fail with continue.

This checks for sigterm but otherwise is identical to the previous
behavior.

ffmpeg.c

@@ -2299,7 +2299,6 @@ static int transcode(OutputFile *output_files,
         int64_t ipts_min;
         double opts_min;
 
-    redo:
         ipts_min= INT64_MAX;
         opts_min= 1e100;
         /* if 'q' pressed, exits */
@@ -2490,7 +2489,7 @@ static int transcode(OutputFile *output_files,
             if (exit_on_error)
                 exit_program(1);
             av_free_packet(&pkt);
-            goto redo;
+            continue;
         }
 
     discard_packet: