Add --dist-one flag to the benchmark script to make it copy a single set of...

            ns = self._run_build(lunch, benchmark_log_dir.joinpath("measured"), benchmark.modules)

            report.duration_ns = ns

            dist_one = self._options.DistOne()

            if dist_one:

                # If we're disting just one benchmark, save the logs and we can stop here.

                self._dist(dist_one)

            else:

                # Postroll builds

                for i in range(benchmark.preroll):

                    ns = self._run_build(lunch, benchmark_log_dir.joinpath(f"post_{i}"),

        return after_ns - before_ns

    def _dist(self, dist_dir):

        out_dir = pathlib.Path("out")

        dest_dir = pathlib.Path(dist_dir).joinpath("logs")

        os.makedirs(dest_dir, exist_ok=True)

        basenames = [

            "build.trace.gz",

            "soong.log",

            "soong_build_metrics.pb",

            "soong_metrics",

        ]

        for base in basenames:

            src = out_dir.joinpath(base)

            if src.exists():

                sys.stderr.write(f"DIST: copied {src} to {dest_dir}\n")

                shutil.copy(src, dest_dir)

    def _write_summary(self):

        # Write the results, even if the build failed or we crashed, including

        # whether we finished all of the benchmarks.

        parser.add_argument("--benchmark", nargs="*", default=[b.id for b in self._benchmarks],

                            metavar="BENCHMARKS",

                            help="Benchmarks to run.  Default suite will be run if omitted.")

        parser.add_argument("--dist-one", type=str,

                            help="Copy logs and metrics to the given dist dir. Requires that only"

                                + " one benchmark be supplied. Postroll steps will be skipped.")

        self._args = parser.parse_args()

            for id in bad_ids:

                self._error(f"Invalid benchmark: {id}")

        # --dist-one requires that only one benchmark be supplied

        if len(self.Benchmarks()) != 1:

            self._error("--dist-one requires that exactly one --benchmark.")

        if self._had_error:

            raise FatalError()

    def Iterations(self):

        return self._args.iterations

    def DistOne(self):

        return self._args.dist_one

    def _init_benchmarks(self):

        """Initialize the list of benchmarks."""

        # Assumes that we've already chdired to the root of the tree.