[Commands] Add entry for xcrun cache
[Commands] Add entry for xcrun cache

-- <rdar://problem/31851566> SwiftPM throws error: couldn't create cache file, during build

vmanot/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,sschiau/swift-package-manager,vmanot/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,vmanot/swift-package-manager,sschiau/swift-package-manager,abertelrud/swift-package-manager,abertelrud/swift-package-manager,JGiola/swift-package-manager,sschiau/swift-package-manager,sschiau/swift-package-manager,JGiola/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,vmanot/swift-package-manager,vmanot/swift-package-manager,JGiola/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager