bytes: add benchmark for LastIndex
Add BenchmarkLastIndexHard[1-3] in preparation for implementing
LastIndex using Rabin-Karp akin to strings.LastIndex
BenchmarkLastIndexHard1-8 500
3162694 ns/op
BenchmarkLastIndexHard2-8 500
3170475 ns/op
BenchmarkLastIndexHard3-8 500
3051127 ns/op
Change-Id: Id99f85f9640e248958f2b4be4dfd8c974e3b50e7
Reviewed-on: https://go-review.googlesource.com/c/go/+/166257
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>