Those helpers were just setting up some extra functions that can be used
on templates, and this can be done already via environment, so let's remove
the helpers completely.
The new xbps-src configuration file is `etc/conf` where you can
add your local overrides from defaults set via `etc/defaults.conf`.
To use this xbps-src, run these steps:
$ make
$ sudo make setup (to make chroot helper setgid)
$ ./xbps-src ...
