A+C: add Yusuke Kagiwada (Individual CLA)

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7292043
diff --git a/AUTHORS b/AUTHORS
index 625a77f..949a060 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -279,6 +279,7 @@
 Yissakhar Z. Beck <yissakhar.beck@gmail.com>
 Yongjian Xu <i3dmaster@gmail.com>
 Yoshiyuki Kanno <nekotaroh@gmail.com> <yoshiyuki.kanno@stoic.co.jp>
+Yusuke Kagiwada <block.rxckin.beats@gmail.com>
 Yuusei Kuwana <kuwana@kumama.org>
 Yuval Pavel Zholkover <paulzhol@gmail.com>
 Ziad Hatahet <hatahet@gmail.com>