Windows: Tidy libcontainer\devices

Signed-off-by: John Howard <jhoward@microsoft.com>

libcontainer/devices/devices_test.go

@@ -1,3 +1,5 @@
+// +build linux freebsd
+
 package devices
 
 import (

libcontainer/devices/devices_unsupported.go

@@ -0,0 +1,3 @@
+// +build windows
+
+package devices

libcontainer/devices/devices_windows.go

@@ -1,16 +0,0 @@
-package devices
-
-import (
-	"github.com/opencontainers/runc/libcontainer/configs"
-)
-
-// TODO Windows. This can be factored out further - Devices are not supported
-// by Windows Containers.
-
-func DeviceFromPath(path, permissions string) (*configs.Device, error) {
-	return nil, nil
-}
-
-func HostDevices() ([]*configs.Device, error) {
-	return nil, nil
-}