Hurd
Homepage: GNU Hurd
Problems
PATH_MAX isn't defined, but it's still used in dlls/ntdll/directory.c (and other irrelevant places).
If you manage to compile wine you'll notice something like "wine client error:0: sendmsg: (os/kern) invalid address", that's because Hurd doesn't fully support socket credentials yet.
See also
Hurd Wine issue
Hurd socket credentials issue
MoinMoin
Python