could hasFlow support multi core?

Hey, I write a codeql-query for chromium. And it works work well.

But I have a problem at here.

1. for query chromium, we always suggest only compile single module(just remove one folder, and create database).
2. But some chromium bug is cross module. It means I could find it once I know which files maybe have bug. It is hard.

I delete all relate `.o` file the bug happened. and create the database. Then my query works well.

But I think the more common situation is :
> I don't know which file will have same pattern, so I just create a big database, which include multi module. Then run my query.

I run my query on this big database, seems it can't handle this. Because of that it will spend too much time on hasFlow Function(I ensure my query is right, because with a small database, it success which I mentioned before).

I search this on github slack, and one people said:

> "I'd guess there is probably one core active that computes data-flow related stuff and all other cores/queries wait for this..."

So I just set --thread=0 in the vscode plugin, but seems it still can't work. Any tips? could make my query run more fast? Thx.

Start by reproducing the query on the large multi-module Chromium database and the smaller database, comparing behavior with --thread=0 in the VS Code plugin. Investigate whether hasFlow work is serialized across cores; done means the multi-module query completes reliably with improved parallel performance.

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