go.blog: add racy example program
go.blog: add racy example program

R=dvyukov, r, remyoudompheng
CC=golang-dev
https://codereview.appspot.com/10447044

bryanxu/go-zh.blog,d0f/go-zh.blog,bryanxu/go-zh.blog,webfd/go-zh.blog,d0f/go-zh.blog,webfd/go-zh.blog