GitLab

It is very useful to see which test commands are executed.
This is of global use, but I wrote it for #11654.

Change-Id: I9bfc8e55d5bef21f4c49b917f58bc9a44aefcade
Reviewed-on: https://go-review.googlesource.com/12510

Reviewed-by: Russ Cox <rsc@golang.org>