[MacPorts] #57234: Some ports are failing to build due to new build system in Xcode 10

[MacPorts]

#57234: Some ports are failing to build due to new build system in Xcode 10
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  Reporter:  mf2k                                |      Owner:  (none)
      Type:  defect                              |     Status:  new
  Priority:  Normal                              |  Milestone:
 Component:  ports                               |    Version:
Resolution:                                      |   Keywords:  xcode10
      Port:  BGHUDAppKit  cotvnc gimp-app        |
  macports-notifier MacVim pinentry-mac          |
  terminal-notifier unison VLC xhyve             |
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Comment (by jmroot):

 Replying to [comment:29 ryandesign]:
 > We are certain that there is a problem with these ports and the new
 build system? We are certain it isn't solved by the change proposed in
 #57137?

 The headermap change is deliberate and not a bug. Ports relying on the old
 behaviour need to be fixed.

 There is a definite bug where a symlink cannot be created when building
 and destrooting in separate xcodebuild invocations. This can easily be
 reproduced with the cocoa app template project included with Xcode. Using
 the old build system works around this problem. I'm not sure if it's
 related to the DerivedData permissions thing.

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Ticket URL: <https://trac.macports.org/ticket/57234#comment:32>
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