unix: map ENETUNREACH to UV_ENETUNREACH
unix: map ENETUNREACH to UV_ENETUNREACH

UV_ENETUNREACH already exists, but was not mapped properly on unix.

unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,unknownbrackets/maxcso,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,urbit/archaeology2,unknownbrackets/maxcso,unknownbrackets/maxcso,unknownbrackets/maxcso,urbit/archaeology2