There is clearly work to do to fix labels and gotos.
The compiler currently hangs on ken/label.go.

For the moment, stop the bleeding.

Fixes the build.

Change-Id: Ib68360d583cf53e1a8ca4acff50644b570382728
Reviewed-on: https://go-review.googlesource.com/11877Reviewed-by: Keith Randall <khr@golang.org>