[MacPorts] #54365: eigen3 fails to configure on Sierra

[MacPorts]

#54365: eigen3 fails to configure on Sierra
------------------------+----------------------
  Reporter:  TimArnold  |      Owner:  eborisch
      Type:  defect     |     Status:  assigned
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:
Resolution:             |   Keywords:
      Port:  eigen3     |
------------------------+----------------------

Comment (by nablamalnabla):

 A similar problem occurs on both of my Macs (iMac 2015, MBP 2015) both
 running Sierra 10.12.5.
 Both Macs recently got an update for Xcode 8.3.3 (if that matters).

 I will add my main.log and also the CMakeError.log / CMakeOutput.log which
 are mentioned in the main.log.

--
Ticket URL: <https://trac.macports.org/ticket/54365#comment:12>
MacPorts <https://www.macports.org/>
Ports system for macOS