[MacPorts] #40656: Use -isystem instead of -I in default configure.cppflags

[MacPorts]

#40656: Use -isystem instead of -I in default configure.cppflags
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  Reporter:  ryandesign@…  |      Owner:  macports-tickets@…
      Type:  enhancement   |     Status:  new
  Priority:  Normal        |  Milestone:  MacPorts Future
 Component:  base          |    Version:  2.2.0
Resolution:                |   Keywords:  haspatch
      Port:                |
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Changes (by ryandesign@…):

 * type:  defect => enhancement


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Ticket URL: <https://trac.macports.org/ticket/40656#comment:1>
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