Older versions of djbdns would pull this in conditional upon USE=doc. This was contrary to the Gentoo policy that man pages should always be installed and that USE=doc is for additional docs, so I've fixed it in the only version of djbdns left in the tree. Now that the only version of djbdns always installs these man pages, the standalone package is not needed.
15 Oct 2014; Michael Orlitzky <mjo@gentoo.org> package.mask: Remove app-doc/djbdns-man from package.mask (gone from tree).