[MacPorts] #37034: plplot: use cmake portgroup

[MacPorts]

#37034: plplot: use cmake portgroup
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  Reporter:  ryandesign@…  |      Owner:  takeshi@…
      Type:  enhancement   |     Status:  reopened
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:
Resolution:                |   Keywords:
      Port:  plplot        |
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Comment (by mojca@…):

 Could you please check this again now that the latest versions of GCC
 ignore the `-arch` flag?

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Ticket URL: <https://trac.macports.org/ticket/37034#comment:8>
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