It has been noticed that commit f88c90f47f
did not only fix NSEC record handling in signed, insecure delegations
prepared using both wildcard expansion and CNAME chaining - it also
inadvertently fixed DS record handling in signed, secure delegations
of that flavor. This is because the 'rdataset' variable in the relevant
location in query_addds() can be either a DS RRset or an NSEC RRset.
Update a code comment in query_addds() to avoid confusion.
Update the comments describing the purpose of query_addds() so that they
also mention NSEC(3) records.
(cherry picked from commit 29d8d35869)
f81c8e3e73