[MacPorts] #62847: opencv4: fix build failures for MacOS 10.7 and 10.8

[MacPorts]

#62847: opencv4: fix build failures for MacOS 10.7 and 10.8
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  Reporter:  mascguy  |      Owner:  mascguy
      Type:  defect   |     Status:  assigned
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:
Resolution:           |   Keywords:
      Port:  opencv4  |
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Comment (by mascguy):

 Replying to [comment:3 kencu]:
 > This is an old issue I have worked around before, several years ago.
 >
 > I will see if I can sort out what I did to fix it.

 Sounds great Ken, I appreciate the help!

 I've reverted to 4.5.0 on MacOS 10.8 and earlier for now, to stop the
 bleeding. But a fix would be great!

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Ticket URL: <https://trac.macports.org/ticket/62847#comment:5>
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