C: add another email of mine.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/102920047

CONTRIBUTORS

@@ -516,7 +516,7 @@ Sergio Luis O. B. Correia <sergio@correia.cc>
 Shane Hansen <shanemhansen@gmail.com>
 Shawn Ledbetter <sledbetter@google.com>
 Shawn Smith <shawn.p.smith@gmail.com>
-Shenghou Ma <minux.ma@gmail.com>
+Shenghou Ma <minux@golang.org> <minux.ma@gmail.com>
 Shivakumar GN <shivakumar.gn@gmail.com>
 Sokolov Yura <funny.falcon@gmail.com>
 Spring Mc <heresy.mc@gmail.com>