analysis/app: convert to new benchstat library

Change-Id: I80e47f05530260b09dd92a04ddbf4799731ee99c
Reviewed-on: https://go-review.googlesource.com/35944
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Quentin Smith <quentin@golang.org>
5 files changed