In case you are wondering why some ports fail to build after upgrading to El Capitan or upgrading Xcode to version 7.2 here is the detailed answer: https://trac.macports.org/wiki/ProblemHotlist#xcode7.2
In my case issuing a simple chmod and chown fixed the issue:
sudo chmod -R g-w $(xcode-select -p)/Library/PrivateFrameworks/CoreSimulator.framework/Versions/A/XPCServices/com.apple.CoreSimulator.CoreSimulatorService.xpc sudo chown -R root:wheel $(xcode-select -p)/Library/PrivateFrameworks/CoreSimulator.framework/Versions/A/XPCServices/com.apple.CoreSimulator.CoreSimulatorService.xpc