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

https://github.com/stenstorp/void-packages gmime3
https://github.com/void-linux/void-packages/pull/11458

gmime3: Fix for ppc
Use same fix as other archs.

A patch file from https://github.com/void-linux/void-packages/pull/11458.patch is attached