cmd/builder: remove unused constants, vars, and function

Change-Id: I50d79135e6f686c3095a45793352dfae1cdadc71
Reviewed-on: https://go-review.googlesource.com/34972
Reviewed-by: Dan Peterson <dpiddy@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed