cmd/cl: now working on Go 1.8
cmd/cl: now working on Go 1.8

Change-Id: I5dd5128746e1ebe19ec47dd4360ba7bea6dda76e
Reviewed-on: https://go-review.googlesource.com/19610
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,golang/build,golang/build,golang/build