Fix compatibility on swift 3.1.1 and 3.0.2.
Fix compatibility on swift 3.1.1 and 3.0.2.

PureSwift/BluetoothLinux,PureSwift/SwiftBlueZ,PureSwift/SwiftBlueZ,PureSwift/BlueZ,PureSwift/BluetoothLinux,PureSwift/BlueZ