benchmarks: add another import comment.

Change-Id: I13861d362b4957d006e94b0314d4e288619652bf
Reviewed-on: https://go-review.googlesource.com/1239
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/bench/bench.go b/bench/bench.go
index dd20b4b..44de9ee 100644
--- a/bench/bench.go
+++ b/bench/bench.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package main
+package main // import "golang.org/x/benchmarks/bench"
 
 import (
 	"golang.org/x/benchmarks/driver"