Re: [PATCH v2 4/5] meson: wire up benchmarks

>
> Wire up benchmarks in Meson. The setup is mostly the same as how we wire
> up our tests. The only difference is that benchmarks get wired up via
> the `benchmark()` option instead of via `test()`, which gives them a bit
> of special treatment:
>
>   - Benchmarks never run in parallel.
>
>   - Benchmarks aren't run by default when tests are executed.
>
>   - Meson does not inject the `MALLOC_PERTURB` environment variable.
>
> Using benchmarks is quite simple:
>
>     ```
>     $ meson setup build
>     # Run all benchmarks.
>     $ meson test -C build --benchmark
>     # Run a specific benchmark.
>     $ meson test -C build --benchmark p0000-*
>     ```

> Other than that the usual command line arguments accepted when running
> tests are also accepted when running benchmarks.
>
> Note that the benchmarking target is somewhat limited because it will
> only run benchmarks for the current build. Other usecases, like running
> benchmarks against multiple different versions of Git, are not currently
> supported. Users should continue to use "t/perf/run" for those usecases.

> +if time.found()
> +  benchmark_environment = test_environment
> +  benchmark_environment.set('GTIME', time.full_path())
> +
> +  foreach benchmark : benchmarks
> +    benchmark(fs.stem(benchmark), shell,
> +      args: [
> +        fs.name(benchmark),
> +      ],
> +      workdir: meson.current_source_dir() / 'perf',
> +      env: benchmark_environment,
> +      depends: test_dependencies + bin_wrappers,
> +      timeout: 0,
> +    )
> +  endforeach
> +endif