[MacPorts] #68731: pinentry-mac does not build with Xcode 15

[MacPorts]

#68731: pinentry-mac does not build with Xcode 15
---------------------------+--------------------
  Reporter:  szhorvat      |      Owner:  (none)
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:
Resolution:                |   Keywords:
      Port:  pinentry-mac  |
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Comment (by FlyingSamson):

 Replying to [comment:5 ryandesign]:
 > So the task would be to discover why this build is deliberately looking
 for the nonexistent macOS 13 SDK and to convince it instead to use the SDK
 that MacPorts told it to use (which is the one you have).

 From what I gathered so far, it is looking for SDK 13.3 because:
 - the `SDKROOT` passed in the failing command is set to
 `/Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk`.
 - This stems from the `xcode` portgroup where `SDKROOT` is set to
 `${configure.sdkroot}`.
 - `configure.sdkroot` by default is set in `portconfigure.tcl` to
 `[portconfigure::configure_get_sdkroot ${configure.sdk_version}]`.
 - `configure.sdk_version` by default is set to `$macosx_sdk_version` which
 by default is set to `$macos_version_major` in `macports.tcl` and results
 in `13` in the failing instances.
 - Then `configure_get_sdkroot` receiving this `sdk_version` of `13` for
 some reason that I do not yet understand must return the path to the
 existing `CLT SDK 13`.

-- 
Ticket URL: <https://trac.macports.org/ticket/68731#comment:8>
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