2011/lex: fix build

Change-Id: I33ecb377b4b88c1ac79a3f691f28dbf25459eaa3
Reviewed-on: https://go-review.googlesource.com/12884
Reviewed-by: Rob Pike <r@golang.org>

2011/lex/r59-lex.go

diff --git a/2011/lex/r59-lex.go b/2011/lex/r59-lex.go
index 16ac257..33af2db 100644
--- a/2011/lex/r59-lex.go
+++ b/2011/lex/r59-lex.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build ignore
+
 package template
 
 import (