Cris Bailiff found this flaw, gethostbyname_r() on linux returns 0 even

when it can't lookup the name (at least in some cases) and thus we need
to make an extra check to detect failures.

lib/hostip.c

@@ -605,6 +605,8 @@ Curl_addrinfo *Curl_getaddrinfo(struct SessionHandle *data,
                                &h_errnop))==ERANGE) {
       step_size+=200;
     }
+    if(!h) /* failure */
+      res=1;
     
 #ifdef MALLOCDEBUG
     infof(data, "gethostbyname_r() uses %d bytes\n", step_size);