[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):

 Update: It looks like this issue started with 4.5.1, which should help
 make it easier to figure out the delta.

 In the interim, I may simply update the port to revert to 4.5.0 for MacOS
 10.8 and earlier, until I've done the analysis.

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Ticket URL: <https://trac.macports.org/ticket/62847#comment:2>
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