[MacPorts] #56417: transcode @1.1.7_21 fails to build with ffmpeg 4

[MacPorts]

#56417: transcode @1.1.7_21 fails to build with ffmpeg 4
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  Reporter:  tehcog     |      Owner:  (none)
      Type:  defect     |     Status:  new
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.4.3
Resolution:             |   Keywords:
      Port:  transcode  |
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Comment (by pmetzger):

 Indeed, a GitHub Pull Request is much easier for us to process. Please
 submit one if possible.

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Ticket URL: <https://trac.macports.org/ticket/56417#comment:4>
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