C: add another email address for David Crawshaw
C: add another email address for David Crawshaw

LGTM=crawshaw
R=crawshaw
CC=golang-codereviews
https://codereview.appspot.com/99180043

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang