New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/issues/24313#issuecomment-675165829

Comment:
From `README.md`

```
Permanent global package build options can be set via `XBPS_PKG_OPTIONS` variable in the
`etc/conf` configuration file. Per package build options can be set via
`XBPS_PKG_OPTIONS_<pkgname>`.
```

And from `common/xbps-src/shutils/common.sh`:

```
        _pkgname=${pkgname//[^A-Za-z0-9_]/_}
        eval pkgopts="\$XBPS_PKG_OPTIONS_${_pkgname}"
        if [ -z "$pkgopts" -o "$pkgopts" = "" ]; then
            pkgopts=${XBPS_PKG_OPTIONS}
        fi
```