libc/netdb: Return EAI_FAMILY in getaddrinfo if the final address is empty

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Change-Id: I510d4e8f79d2b4e78c550b35b7b07f2d0943e32d

libs/libc/netdb/lib_getaddrinfo.c

@@ -333,7 +333,7 @@ int getaddrinfo(FAR const char *hostname, FAR const char *servname,
           prev_ai = ai;
         }
 
-      return OK;
+      return (*res != NULL) ? OK : EAI_FAMILY;
     }
 
   return h_errno;