A+C: add Robert Dinu (Individual CLA)

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7386045
fmt: fix width for nil values

Apply width when using Printf with nil values.
Fixes issue 4772.

R=r, adg
CC=golang-dev
https://codereview.appspot.com/7314114

Committer: Rob Pike <r@golang.org>