BIND 10 #2165: update Message::addRRset() to be unaware of signedness

[BIND 10 Development]

#2165: update Message::addRRset() to be unaware of signedness
-------------------------------------+-------------------------------------
            Reporter:  jinmei        |                        Owner:
                Type:  task          |  UnAssigned
            Priority:  medium        |                       Status:  new
           Component:  libdns++      |                    Milestone:  New
           Sensitive:  0             |  Tasks
         Sub-Project:  DNS           |                     Keywords:
Estimated Difficulty:  0             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |  scalable inmemory
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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 This is one building block of #2163.

 What we do is:
 - adjust counts_[section] for any RRSIGs using
   `RRset::getSIGRdataCount`() (introduced in #2164)
 - remove the 'sign' parameter of `Message::addRRset()`
 - stop extracting the RRSIG

 Also:
 - update the following part of Zonefinder::find() doc:
 {{{#!cpp
     /// - \c FIND_DNSSEC Request that DNSSEC data (like NSEC, RRSIGs) are
     ///   returned with the answer. It is allowed for the data source to
     ///   include them even when not requested.
 }}}
   saying DNSSEC data are only returned when FIND_DNSSEC is specified
   (the current implementation should already meet this requirement).
   Note: without this condition we cannot remove the 'sign' parameter
   of Message::addRRset()

 Finally: update affected tests.

 This will be an incomplete update: we also need to update the
 rendering logic so the RRSIGs will be correctly rendered.  But
 combining these will be too big a task, so I suggest we stop here, not
 merging (temporarily disabling any failed tests due to this particular
 point).  The rest of the work will go to a separate ticket.

 Depends on #2164.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2165>
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BIND 10 Development