cmd/go: test -i should not disable -c         Fixes issue 3104.
cmd/go: test -i should not disable -c
        Fixes issue 3104.

R=golang-dev, rsc
CC=golang-dev
http://codereview.appspot.com/5699088

Committer: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

tav/go,tav/go,tav/go,tav/go,tav/go,tav/go,tav/go