[MacPorts] #63484: updated Portfile for py-pyfftw

[MacPorts]

#63484: updated Portfile for py-pyfftw
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  Reporter:  bernard-giroux  |      Owner:  lpsinger
      Type:  update          |     Status:  assigned
  Priority:  Normal          |  Milestone:
 Component:  ports           |    Version:
Resolution:                  |   Keywords:
      Port:  py-pyfftw       |
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Comment (by bernard-giroux):

 Hi

 I added the flag because otherwise the port does not install.  The
 developers of pyfftw use a custom approach to find the fftw library, and
 the flag is needed for that purpose.

 It looks like they are aware that this flag is needed on macOS to get the
 port installed, but for now they have not updated their script.

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Ticket URL: <https://trac.macports.org/ticket/63484#comment:2>
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