- removed 'ifdef INET6' (libbind's getaddrinfo should always be buildable
with the INET6 part.)
- use EAI_NONAME instead of EAI_NODATA (this is an API issue. I'll raise
it at the group working on the API).
- use h_errno instead of __h_errno.
- clarification on using interface names as link IDs of IPv6 link-local
addresses. (not all OSes support this.)