Feature Request: Add options to disable build in parallel.

[filzrev]

When running benchmark with multiple Jobs that use WithCustomBuildConfiguration.
Parallel build is failed. and switching to sequential build.

BenchmarkDotNet/src/BenchmarkDotNet/Running/BenchmarkRunnerClean.cs

Lines 365 to 393 in f4bfcd6

	logger.WriteLineHeader($"// ***** Building {buildPartitions.Length} exe(s) in Parallel: Start *****");
	var buildLogger = buildPartitions.Length == 1 ? logger : NullLogger.Instance; // when we have just one partition we can print to std out
	var beforeParallelBuild = globalChronometer.GetElapsed();
	var buildResults = buildPartitions
	.AsParallel()
	.Select(buildPartition => (Partition: buildPartition, Result: Build(buildPartition, rootArtifactsFolderPath, buildLogger)))
	.AsSequential() // Ensure that build completion events are processed sequentially
	.Select(build =>
	{
	// If the generation was successful, but the build was not, we will try building sequentially
	// so don't send the OnBuildComplete event yet.
	if (buildPartitions.Length <= 1 || !build.Result.IsGenerateSuccess || build.Result.IsBuildSuccess)
	eventProcessor.OnBuildComplete(build.Partition, build.Result);
	return build;
	})
	.ToDictionary(build => build.Partition, build => build.Result);
	var afterParallelBuild = globalChronometer.GetElapsed();
	logger.WriteLineHeader($"// ***** Done, took {GetFormattedDifference(beforeParallelBuild, afterParallelBuild)} *****");
	if (buildPartitions.Length <= 1 || !buildResults.Values.Any(result => result.IsGenerateSuccess && !result.IsBuildSuccess))
	return buildResults;
	logger.WriteLineHeader("// ***** Failed to build in Parallel, switching to sequential build *****");

I though parallel build failure is caused because obj\project.assets.json is shared between build configurations.
And wrong dependencies are used for parallel build.

Is is able to add options to disable parallel build?
And If it can disable parallel build. It will be a workaround for #2425 also.

[timcassell]

I think it's a reasonable request. Your particular issue should be fixed by #2676, but I imagine there could be other reasons to want to build sequentially (like maybe using older runtimes where the fix won't work). Feel free to send a PR.