Change syscall result

[tgrez]

Verified for 64-bit and 32-bit arch.

What do you think about adding this functionality?

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This change is 

[qrilka]

Hi @tgrez
How did you test it on 32bit? I wanted to write a script using nix+qemu at least to check compilation of the project. But I didn't start writing it yet.
I didn't check the PR contents yet - will do it in the evening.

[qrilka]

Looks like a cool addition

[qrilka]

@tgrez do you have any specific use case for this feature?

[tgrez]

Thanks!

Yes, I do :) one example can be found in here: https://github.com/tgrez/kafka-producer-idempotence
I'm writing a blog post describing this example and Hatrace in general. If you want I can disclose the preview ;)

The 32-bit verification was done just on bare virtualbox vm.

[qrilka]

That's great to see new real life example for hatrace!
Please create a PR adding a link to your blog post to README when it will get published.
Thanks.

[nh2]

That works, thanks!

And great post by the way!