Xgetaddrinfo makes rendezvous DAG for SOCK_STREAM

If a resolv.conf is present and it lists a rendezvous service DAG, the
call to Xgetaddrinfo results in a DAG with the rendezvous as a fallback.
App gives socktype in Xgetaddrinfo() to get RV DAG

The application is required to provide a hints option with socktype set
to SOCK_STREAM for Xgetaddrinfo() to look for a rendezvous DAG and add
it as fallback for the DAG it is returning.
Stream packets destined for SOCK_RAW deliver as is

If a stream packet arrives but the listening port is a raw socket, we
deliver the packet as is to the application without stripping the XIP
header.
Framework for rendezvous service.

A main loop listening on two sockets for control and data messages
respectively. No actual processing of messages yet.