After searching at great length, and following many blind alleys, I found an imprecise reference to the problem that I was having. So, to save you that time, here’s the deal.
If you want to build webalizer with DNS lookup abilities, ie, using the –enable-dns flag to ./configure, you need to edit two files.
In webalizer.c you need to change
In dns_resolv.c you need to make exactly the same change.
That is all.