Auto merge of #1297 - RalfJung:win-ticks, r=RalfJung
Auto merge of #1297 - RalfJung:win-ticks, r=RalfJung

correct factual mistake in Windows message

Also use `+` instead of `checked_add().unwrap()` (which is equivalent).

Cc @JOE1994

rust-lang/miri,rust-lang/miri,rust-lang/miri,rust-lang/miri