A patch to bypass MS' sillyness with regard to IPv6 and getaddrinfo().

The CURLDEBUG part is to avoid redefinition warning caused by memdebug.h. If
ENABLE_IPV6 isn't enabled, it doesn't matter since we never call
getaddrinfo(). Allthough we could to support weird protocols like SOCK_RDM
that Win-2K/XP has.