io.sockets: add word addrinfo-error to signal host lookup failures

In the http daemon I'm writing I need to handle resolve-host failures. Because of my crappy connection I will often get the "Temporary failure in name resolution" which I want to handle by retrying. Factor makes that hard because the actual error thrown is on Linux a string object and on Windows a winsock-exception. 

So to make that easier to handle, I've created a new error type `addrinfo-error`, which is the same on all platforms, with the error code and message in it.