net: fix build

R=adg
CC=golang-dev
https://golang.org/cl/3982051
diff --git a/src/pkg/net/timeout_test.go b/src/pkg/net/timeout_test.go
index 3594c0a..09a257d 100644
--- a/src/pkg/net/timeout_test.go
+++ b/src/pkg/net/timeout_test.go
@@ -46,8 +46,12 @@
 }
 
 func TestTimeoutTCP(t *testing.T) {
-	// 74.125.19.99 is www.google.com.
-	// could use dns, but dns depends on
-	// timeouts and this is the timeout test.
-	testTimeout(t, "tcp", "74.125.19.99:80", false)
+	// set up a listener that won't talk back
+	listening := make(chan string)
+	done := make(chan int)
+	go runServe(t, "tcp", "127.0.0.1:0", listening, done)
+	addr := <-listening
+
+	testTimeout(t, "tcp", addr, false)
+	<-done
 }