[MacPorts] #54198: upgrade: port:gcc7

[MacPorts]

#54198: upgrade: port:gcc7
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  Reporter:  RJVB    |      Owner:
      Type:  update  |     Status:  new
  Priority:  Normal  |  Milestone:
 Component:  ports   |    Version:
Resolution:          |   Keywords:  haspatch
      Port:  gcc7    |
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Changes (by RJVB):

 * Attachment "patch-use-libcxx.diff" added.


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Ticket URL: <https://trac.macports.org/ticket/54198>
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