fix: reduce_f won't work with single bit operands

[gottschalkm]

The or_reduce_f, and_reduce_f, and xor_reduce_f won't work for single bit as the condition fails.
This produces some bugs in the interrupt controller (signal irq_fire) if only one interrupt line is used.

[stnolting]

Thanks for fixing!

[umarcor]

@stnolting I think you are misunderstanding the purpose of label good first issue. That is typically used for new contributors who want to help with some task, so they can more easily find pending issues to help at. However, here you used it "post-mortem", to indicate that you think this was a good contribution for a first time contributor. For that purpose, I believe it's better to use reactions (:heart:) or to be vocal about it:

@gottschalkm this was a nice fix! Congrats and welcome to the list of contributors!

Naturally, you are free to use labels as you want. However, this specific label is a convention across multiple repos, similarly to the hacktoberfest.

[stnolting]

I'm still not sure how to handle all those labels - maybe we ( I ) need an issue/discussion to define a list of labels... 😅
Anyway, thanks for clearing 😄