cmd/coordinator: delete some code earlier copied to the buildgo package
cmd/coordinator: delete some code earlier copied to the buildgo package

Change-Id: I7244c0d272a112adb6682793eca8563fc3c78e49
Reviewed-on: https://go-review.googlesource.com/51433
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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