all: don't refer to code.google.com/p/go{,-wiki}/

Only documentation / comment changes. Update references to
point to golang.org permalinks or go.googlesource.com/go.
References in historical release notes under doc are left as is.

Change-Id: Icfc14e4998723e2c2d48f9877a91c5abef6794ea
Reviewed-on: https://go-review.googlesource.com/4060
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/math/big/int_test.go b/src/math/big/int_test.go
index 1418dca..cb8c76b 100644
--- a/src/math/big/int_test.go
+++ b/src/math/big/int_test.go
@@ -655,7 +655,7 @@
 	"10953742525620032441",
 	"17908251027575790097",
 
-	// http://code.google.com/p/go/issues/detail?id=638
+	// http://golang.org/issue/638
 	"18699199384836356663",
 
 	"98920366548084643601728869055592650835572950932266967461790948584315647051443",