There's a merged pull request on the void-packages repository

xbps-src: have cmdline arguments take precedence over config files
https://github.com/void-linux/void-packages/pull/19055

Description:
This way we can e.g. have `XBPS_MAKEJOBS` set in config file while overriding it with `-j`.

This also notably changes some other semantics. Particularly:

1) Links in `hostdir`/`masterdir` are now always resolved regardless of how they are provided (via arg or via config)
2) The `-o` option for `xbps-src` specifying build options merges with whatever was previously specified in config file, instead of overriding. This makes more sense overall as options specified on command line
actually apply to every package built during that run.

This PR is in preparation for support for custom configurations via `-c configname`.