[Generator::Xcconfig] Properly handle the inherited key.
[Generator::Xcconfig] Properly handle the inherited key.

See #653

mglidden/CocoaPods,ashfurrow/CocoaPods,orta/CocoaPods,Ashton-W/CocoaPods,segiddins/CocoaPods,vivekshukla-mob-ibtech/Repository,mglidden/CocoaPods,mglidden/CocoaPods