[MacPorts] #59398: ICU 65 fails to build on 10.6

[MacPorts]

#59398: ICU 65 fails to build on 10.6
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  Reporter:  rmottola  |      Owner:  ryandesign
      Type:  defect    |     Status:  closed
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:  fixed     |   Keywords:
      Port:  icu       |
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Comment (by rmottola):

 I confirm that the fix proposed by kencu worked - I upgraded ICU.
 About circular dependencies I don't know.

 Attention that ICU upgrade calls alot of fallout: it breaks libxml2 and
 with that it breaks all clang versions after 5.0 and many more packages,
 causing a big issue, since even rev-dep detects only some and would always
 use latest (broken) clang versions to rebuild, since revdep does not
 accept/respect configure.compiler.

 I uninstalled (deactivating is also enough.. but thought about it only at
 the second step) gradually clang 9, clang 8.... until clang 6. With clang
 5 revdep was able to rebuild all dependencies, then i activated/installed
 newer clang versions again.

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Ticket URL: <https://trac.macports.org/ticket/59398#comment:7>
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