cmd/debugnewvm: add support for doing a test build too
cmd/debugnewvm: add support for doing a test build too

Change-Id: Ic67032554ab77f69176b774a8c33523062f21c88
Reviewed-on: https://go-review.googlesource.com/51431
Reviewed-by: Jeff Johnson <e0aeede46a59107c4d834f64851ee491686571e7@google.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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