- Updates window.sys to version 0.58. - A key change to this version is that the HANDLE type is now `*mut c_void`, so the code was changed to accomodate this. - An important change is the manual implementation of the `Send` trait for `ChildExistWatcher`. The trait can no longer derived automatically because `*mut c_void` is not Send. However, pointers are not Send more as a lint to developers (eg: a pointer to Rc<T> would be safe), but `c_void` is Send and therefore it should be fine to derive it manually for the pointer. See https://doc.rust-lang.org/nomicon/send-and-sync.html for details.