Switch winapi dependency to windows/windows-sys in rand_jitter

[atouchet]

The winapi crate no longer appears to be maintained and there are now official windows/windows-sys crates from Microsoft. As such rand_jitter should probably transition from using winapi to windows/windows-sys.

[dhardy]

Understood.

rand_jitter itself is barely maintained and likely little used; if you are a user I would encourage you to make a PR yourself. Otherwise, maybe this can happen after the next rand_core release.