[MacPorts] #54289: libcxx{,-abi} : upgrade + "runtime" variant

[MacPorts]

#54289: libcxx{,-abi} : upgrade + "runtime" variant
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  Reporter:  RJVB              |      Owner:  jeremyhu
      Type:  update            |     Status:  assigned
  Priority:  Normal            |  Milestone:
 Component:  ports             |    Version:
Resolution:                    |   Keywords:  haspatch
      Port:  libcxxabi libcxx  |
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Comment (by RJVB):

 Updated for port:libcxx 5.0.1, adds a wrapper script to run only specific
 applications with the newer libc++.

 Also, a tweak that makes the build respect `configure.optflags`. If you're
 going to use a custom-built libc++ it could just as well be one with
 additional optimisation or rather optimal debugging aptitudes.

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Ticket URL: <https://trac.macports.org/ticket/54289#comment:4>
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