add hacks for windows in Lwt_unix
add hacks for windows in Lwt_unix

Ignore-this: 48811fcae1e97a8156e69d43f9f8df22

darcs-hash:20100401000442-c41ad-25399f24c752ce4a3e92965d34838b84fcfbfef5.gz

avsm/lwt-OLD,avsm/lwt-OLD