[MacPorts] #59515: [icu] : support building with llvm-ar

[MacPorts]

#59515: [icu] : support building with llvm-ar
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  Reporter:  RJVB         |      Owner:  catap
      Type:  enhancement  |     Status:  closed
  Priority:  Normal       |  Milestone:
 Component:  ports        |    Version:
Resolution:  fixed        |   Keywords:  haspatch
      Port:  icu          |
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Comment (by RJVB):

 So llvm 5 and earlier do not support `r -c`, but all `ar`
 versions/variants that I tried support the traditional form `rc`,
 including the basic `ar` from the system toolchain.
 Alternatively the entire change to `ARFLAGS` could be removed because
 there is little reason to suppress the single line warning about creating
 a new archive in MacPorts builds. That might not be the case for regular
 builds that want to limit output so I'm not certain how appropriate
 upstreaming this change is. I'll leave that to the port maintainer anyway.

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Ticket URL: <https://trac.macports.org/ticket/59515#comment:11>
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