There's a merged pull request on the void-packages repository

arb: update to 2.21.0.
https://github.com/void-linux/void-packages/pull/33170

Description:
I use the packages affected by the proposed changes on a regular basis and confirm this PR works for me

- Added a (temporary) patch to fix test on 32bit, already merged upstream, see https://github.com/fredrik-johansson/arb/issues/379
- conditional for musl not needed anymore after https://github.com/fredrik-johansson/arb/commit/c713d91280472d572fc43a64db43def73d650d11 (see https://github.com/fredrik-johansson/arb/pull/376)