Don't segfault for --help of single.sh build of OLDTOY commands that use another command's help.
Have OLDTOY emit (redundant) function prototype so single.sh can build OLDTOY standalone (if it has its own config symbol).
Untangle id/groups/logname so single.sh can build each one standalone.
Allow single.sh to build more than one command per invocation.
Cleanup pass on groupdel.
Multi-build single.sh should exit with an error when build breaks.