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

https://github.com/tornaria/void-packages libmpc
https://github.com/void-linux/void-packages/pull/32658

libmpc: update to 1.2.1.
I compiled and doctested sage-9.4 with this PR + other updates and new packages. All working fine.

A patch file from https://github.com/void-linux/void-packages/pull/32658.patch is attached