net: fix TestLookupCNAME

The CNAME record for www.iana.org seems to have been changed, causing
test failures.

Change the test to just use www.golang.org, so we have more control and
awareness of such changes in the future.

Fixes #80212

Change-Id: I7b11bb8f90fe366db019dab1f8d9a1cf6a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/795840
Auto-Submit: Nicholas Husin <husin@google.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Nicholas Husin <husin@google.com>

src/net/lookup_test.go

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index 42211ed..afa7e4c 100644
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -335,8 +335,8 @@
 var lookupCNAMETests = []struct {
 	name, cname string
 }{
-	{"www.iana.org", "icann.org."},
-	{"www.iana.org.", "icann.org."},
+	{"www.golang.org", "golang.org."},
+	{"www.golang.org.", "golang.org."},
 	{"www.google.com", "google.com."},
 	{"google.com", "google.com."},
 	{"cname-to-txt.go4.org", "test-txt-record.go4.org."},