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

https://github.com/xtraeme/void-packages travis-nprocs
https://github.com/void-linux/void-packages/pull/12119

travis/build.sh: use -jX in xbps-src.
Do not rely on nproc(1) being available.

Signed-off-by: Juan RP <xtraeme@gmail.com>

A patch file from https://github.com/void-linux/void-packages/pull/12119.patch is attached