message: change cfg gate to enable testing Instant subtraction in Windows
diff: @@ -25,7 +25,7 @@ fn main() {
  let now2 = Instant::now();
  assert!(now2 > now1);
  - #[cfg(target_os = "linux")] // TODO: macOS does not support Instant subtraction
  + #[cfg(not(target_os = "macos"))] // TODO: macOS does not support Instant subtraction
  {
  let diff = now2.duration_since(now1);
  assert_eq!(now1 + diff, now2);
  