[MacPorts] #67977: gtk4 uses Linux flags on Mac which breaks the build

[MacPorts]

#67977: gtk4 uses Linux flags on Mac which breaks the build
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  Reporter:  barracuda156  |      Owner:  mascguy
      Type:  defect        |     Status:  closed
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.8.1
Resolution:  invalid       |   Keywords:
      Port:  gtk4          |
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Comment (by barracuda156):

 P.S. I don’t really get why this is invalid. This looks like a genuine bug
 unrelated to OS version.

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Ticket URL: <https://trac.macports.org/ticket/67977#comment:4>
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