[MacPorts] #56185: npth requires unnamed semaphores; provide those for Darwin 9 and earlier

[MacPorts]

#56185: npth requires unnamed semaphores; provide those for Darwin 9 and earlier
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  Reporter:  ccorn   |      Owner:  (none)
      Type:  defect  |     Status:  new
  Priority:  Normal  |  Milestone:
 Component:  ports   |    Version:
Resolution:          |   Keywords:
      Port:  npth    |
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Comment (by kencu):

 basically, nobody was motivated to move it along. I never used npth or
 gpu-agent, so didn't come across it.

 Looking at the header and the source file, it would seem to be a trivial
 addition to legacysupport. But someone would need to figure out how this
 made it's way into Darwin, what systems need it, and (ideally) how to make
 a simple test for it.

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Ticket URL: <https://trac.macports.org/ticket/56185#comment:9>
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