Fix "dial tcp 127.0.0.1:63890: getsockopt: connection refused"

Since 2d04cf08cb3413ba9c7271a1884ceca00c56c7e2 ("Test with IPv6 by
default, and IPv4 only if that fails."), the test runner listens on ::1
by default instead of 127.0.0.1.

tls_shim.go

@@ -53,7 +53,7 @@ func main() {
 	}
 
 	for i := 0; i < *resumeCount+1; i++ {
-		conn, err := net.Dial("tcp", net.JoinHostPort("127.0.0.1", *port))
+		conn, err := net.Dial("tcp", net.JoinHostPort("localhost", *port))
 		if err != nil {
 			log.Fatal(err)
 		}