* ext/socket/extconf.rb: use headers instead of "netdb.h" in checking
getnameinfo() and getaddrinfo() because Windows doesn't have it.
see [ruby-dev:37757].
* ext/socket/sockport.h (SA_LEN): use sockaddr_in6 when defined AF_INET6
if INET6 is not defined. winsock2's getaddrinfo() returns
sockaddr_in6 if ipv6 is available.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@21543 b2dd03c8-39d4-4d8f-98ff-823fe69b080e