Extract mknod, umask, lstat to pkg/system

Some parts of pkg/archive is called on both client/daemon code. To get
it compiling on Windows, these funcs are extracted into files with
build tags.

Signed-off-by: Ahmet Alp Balkan <ahmetb@microsoft.com>

system/mknod_windows.go

@@ -0,0 +1,12 @@
+// +build windows
+
+package system
+
+func Mknod(path string, mode uint32, dev int) error {
+	// should not be called on cli code path
+	return ErrNotSupportedPlatform
+}
+
+func Mkdev(major int64, minor int64) uint32 {
+	panic("Mkdev not implemented on windows, should not be called on cli code")
+}