[MacPorts] #53470: port:audacity build fix (and upgrade for audacity-devel)

[MacPorts]

#53470: port:audacity build fix (and upgrade for audacity-devel)
-----------------------+---------------------------------
  Reporter:  RJVB      |      Owner:
      Type:  defect    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:  haspatch maintainer
      Port:  audacity  |
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Comment (by mf2k):

 I tried your latest portfile and patches, but I see this message from the
 app: "Audacity attempted to use FFmpeg to import an audio file, but the
 libraries were not found."

 I have it installed:
 {{{
 $ port installed ffmpeg-devel
 The following ports are currently installed:
   ffmpeg-devel @20170119_4+gpl2+gpl3+nonfree (active)
 }}}

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Ticket URL: <https://trac.macports.org/ticket/53470#comment:4>
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