Fix overflow in duration

[TethysSvensson]

When trying to wait for Duration::MAX, mio will panic with an overflow. This is a work-around for that behavior.

[Thomasdezeeuw]

Could you also fix it for Windows:

mio/src/sys/windows/iocp.rs

Line 231 in 7ed74bf

let dur_ms = (dur + Duration::from_nanos(999_999)).as_millis();

?

[TethysSvensson]

Could you also fix it for Windows:

mio/src/sys/windows/iocp.rs

Line 231 in 7ed74bf

let dur_ms = (dur + Duration::from_nanos(999_999)).as_millis();

?

Done

[TethysSvensson]

@Thomasdezeeuw I've updated the PR to fix some issues encountered by the CI.

[Thomasdezeeuw]

Thanks @TethysSvensson