resolvers: no more using AI_CANONNAME

No resolver anymore needs to use AI_CANONNAME and do reverse
lookups.  We should work hard to avoid having code that relies on
it.

lib/hostthre.c

@@ -561,9 +561,7 @@ Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
   memset(&hints, 0, sizeof(hints));
   hints.ai_family = pf;
   hints.ai_socktype = conn->socktype;
-#if 0 /* removed nov 8 2005 before 7.15.1 */
-  hints.ai_flags = AI_CANONNAME;
-#endif
+
   snprintf(sbuf, sizeof(sbuf), "%d", port);
 
   /* fire up a new resolver thread! */