[ofw] Native IB connection setup.

[Hefty, Sean]

> what is AF_IB? Is this something related to sockets or multicast (or both)?

AF_IB is the IB equivalent to AF_INET or AF_INET6.  There's a sockaddr_ib structure that allows the user to specify native IB addressing (i.e. GID + PKey + ServiceID) during connection setup.  The RDMA CM supports this.

AF_IB fell out of work on the ibacm, which allowed user space to perform address resolution (IP -> IB).  ibacm was able to convert an IP address into an IB path record.  However, without kernel support for direct use of native IB addressing, the IP address was still passed to the kernel, forcing kernel address resolution using IPoIB.  AF_IB can be used to avoid any kernel address or route resolution.

- Sean