cmd/go: racewalk: fix nested struct handling Fixes issue 4424. Fixes issue 4425.
cmd/go: racewalk: fix nested struct handling
Fixes issue 4424.
Fixes issue 4425.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/6849093
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go