cmd/go: fixed panic on `go clean -n` and `go clean -x`.         also made generated scripts act more like running go clean itself
cmd/go: fixed panic on `go clean -n` and `go clean -x`.
        also made generated scripts act more like running go clean itself

R=golang-dev
CC=golang-dev, rsc
http://codereview.appspot.com/5624049

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

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