There is an updated pull request by ericonr against master on the void-packages repository

https://github.com/ericonr/void-packages sdcc-update
https://github.com/void-linux/void-packages/pull/20434

sdcc: update to 4.0.0 and update hostmakedepends
Automake and texinfo had to be added to hostmakedepends.

@maxice8 I'm tagging you here because you were the one responsible for the previous SDCC PRs.

EDIT: the builds timed out, which was predictable, if unfortunate.

A patch file from https://github.com/void-linux/void-packages/pull/20434.patch is attached