[MacPorts] #40174: upgrade mingw and add win64 cross-compiler

[MacPorts]

#40174: upgrade mingw and add win64 cross-compiler
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  Reporter:  sam.halliday@…  |      Owner:  macports-tickets@…
      Type:  update          |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  ports           |    Version:  2.2.0
Resolution:                  |   Keywords:
      Port:                  |
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Comment (by sam.halliday@…):

 this should be against i386-mingw32-gcc (but I can't seem to change that
 anymore)

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Ticket URL: <https://trac.macports.org/ticket/40174#comment:1>
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