[MacPorts] #56433: update gmt4 to 4.5.17

[MacPorts]

#56433: update gmt4 to 4.5.17
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  Reporter:  fvaccari  |      Owner:  tenomoto
      Type:  update    |     Status:  assigned
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:
      Port:  gmt4      |
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Comment (by fvaccari):

 That wiki entry is describing git operations through Terminal, but I acted
 through the Web Interface. There was still a green button to be pushed
 there, and I think I've now completed the pull request choosing the
 "Rebase and commit" option, that I've read somewhere was the preferred
 one. It now says


 {{{
 Pull request successfully merged and closed
 You’re all set—the fvaccari-patch-1 branch can be safely deleted.
 }}}

 I hope I did it right...

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Ticket URL: <https://trac.macports.org/ticket/56433#comment:5>
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