Write queue after connect windows

Is this an issue that should be addressed? The flags are the same:

`src/unix/internal.h`:
```c
/* handle flags */
enum {
  UV_CLOSING              = 0x01,   /* uv_close() called but not finished. */
  UV_CLOSED               = 0x02,   /* close(2) finished. */
```

`src/win/internal.h`
```c
#define UV_HANDLE_CLOSED                        0x00000002
/* uv-common.h: #define UV__HANDLE_CLOSING      0x00000001 */
```

Seems the difference is one uses an `enum` and the other uses `#define`'s. But the flag values are the same. So you could make an alias of `UV_CLOSED` and `UV_CLOSING` in `src/win/internal.h` and use `uv__is_closing` for consistency.