There is a new pull request by ndowens against master on the void-packages repository

https://github.com/ndowens/void-packages libdrm
https://github.com/void-linux/void-packages/pull/16071

libdrm: update to 2.4.100
Built against a few packages that uses it and also ran radeontop fine

A patch file from https://github.com/void-linux/void-packages/pull/16071.patch is attached