[MacPorts] #57761: netgen: add opencascade variant

[MacPorts]

#57761: netgen: add opencascade variant
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  Reporter:  mbrethen     |      Owner:  MarcusCalhoun-Lopez
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:  2.5.4
Resolution:               |   Keywords:
      Port:  netgen       |
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Comment (by mf2k):

 As I mentioned in #57772, please instead attach a unified diff of the
 Portfile.

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Ticket URL: <https://trac.macports.org/ticket/57761#comment:2>
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