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

https://github.com/alekseyt/void-packages mingw-v8
https://github.com/void-linux/void-packages/pull/25576

cross-x86_64-w64-mingw32: update to 8.0.0
* Mingw-w64 8.0.0
* GCC 10.2.0
* Other dependencies harmonized with mainline
* Incorporates #16891

A patch file from https://github.com/void-linux/void-packages/pull/25576.patch is attached