[MacPorts] #53546: Add IPv4 and IPv6 flag (-4, -6)

[MacPorts]

#53546: Add IPv4 and IPv6 flag (-4, -6)
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  Reporter:  l2dy         |      Owner:
      Type:  enhancement  |     Status:  new
  Priority:  Normal       |  Milestone:
 Component:  base         |    Version:
Resolution:               |   Keywords:
      Port:               |
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Comment (by l2dy):

 MacPorts could not magically pick the right stack so I have to manually
 specify that.

 The situation is rather complicated. In my school, IPv6 is not metered
 while IPv4 is, so I'd prefer download only using IPv6 (use `-6`). However,
 only wired connection has IPv6 Internet access, the school Wi-Fi gives me
 an IPv6 address and gateway but has no IPv6 connectivity (use `-4`).

 My proposal is to add the two global options to port(1) so I could pick
 the right stack manually. The expected behavior is the same as curl's.

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Ticket URL: <https://trac.macports.org/ticket/53546#comment:2>
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