all: add go.mod

Commands run:
	go mod init
	go mod edit -go=1.11
	go mod tidy
	go list -m all
	go test ./...

Updates golang/go#30228

Change-Id: I43900a3d2b59ddb7701436a652ac00e35a49c69d
Reviewed-on: https://go-review.googlesource.com/c/benchmarks/+/167177
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2 files changed