src: minor API change uv_ipx_addr and uv_poll_start

* Change uv_ip4_addr and uv_ip6_addr to take an unsigned short as
  port number instead of int(signed).
* Change uv_poll_start events to unsigned int instead of an
  int(signed). This also changes uv_poll_t.
Merge branch 'dev/win32-minor-fixes' of https://github.com/zerhacken/libuv into dev/win32-minor-fixes