A+C: add Gustavo Niemeyer (individual CLA)

R=adg
CC=golang-dev
https://golang.org/cl/1693046
diff --git a/AUTHORS b/AUTHORS
index 3577cd9..b41da7d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -37,6 +37,7 @@
 Firmansyah Adiputra <frm.adiputra@gmail.com>
 Giles Lean <giles.lean@pobox.com>
 Google Inc.
+Gustavo Niemeyer <gustavo@niemeyer.net>
 Hector Chu <hectorchu@gmail.com>
 Icarus Sparry <golang@icarus.freeuk.com>
 Isaac Wagner <ibw@isaacwagner.me>