compilebench contains three different types of benchmarks and we're
about to add a fourth. Currently we dispatch based on name. This CL
cleans this up so the list of benchmarks points to how to run each
benchmark. It also joins together common error-reporting paths.
Change-Id: Icd4f77bdda9776863792dcd85f27b17829a833e6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/175799
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>