regexp: fix imports in the middle of the license header

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/129620043

src/pkg/regexp/onepass.go

 // Copyright 2014 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
 
 package regexp
 
@@ -9,9 +11,6 @@ import (
 	"unicode"
 )
 
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
 // "One-pass" regexp execution.
 // Some regexps can be analyzed to determine that they never need
 // backtracking: they are guaranteed to run in one pass over the string