fix netdb/getaddrinfo unit test

tests/netdb/getaddrinfo.c

@@ -31,18 +31,24 @@ int main(void) {
         case AF_INET:
             ptr = &((struct sockaddr_in *) res->ai_addr)->sin_addr;
             break;
+#ifdef AF_INET6
         case AF_INET6:
             ptr = &((struct sockaddr_in6 *) res->ai_addr)->sin6_addr;
             break;
+#endif
+        default:
+            ptr = NULL;
         }
-        inet_ntop(res->ai_family, ptr, addrstr, INET6_ADDRSTRLEN);
+        if (ptr) {
+            inet_ntop(res->ai_family, ptr, addrstr, INET6_ADDRSTRLEN);
 
-        printf(
-            "IPv%d address: %s (%s)\n",
-            res->ai_family == AF_INET6 ? 6 : 4,
-            addrstr,
-            res->ai_canonname
-        );
+            printf(
+                "IPv%d address: %s (%s)\n",
+                res->ai_family == AF_INET ? 4 : 6,
+                addrstr,
+                res->ai_canonname
+            );
+        }
 
         res = res->ai_next;
     }