Possible leak in uv__init_overlapped_dummy() for win

[escherstair]

Function https://github.com/libuv/libuv/blob/285a5ea819035ff777b8b7c6a367f3f5b55d8809/src/win/poll.c#L55 creates an event called event, whichis never discarded. Maybe a CloseHandle(event); is necessary before the end of the function uv__init_overlapped_dummy()

Do you agree? If this is the case, I can open a PR