fix: populate ldns submodule and add autotools to LDNS build stage

- Re-cloned zonemaster-ldns with --recurse-submodules so the bundled
  ldns C library source (including Changelog and configure.ac) is present
- Added autoconf, automake, libtool to Dockerfile.backend ldns-build stage
  so libtoolize + autoreconf can generate ldns/configure during make

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

zonemaster-ldns/ldns/contrib/DNS-LDNS/lib/DNS/LDNS/DNSSecName.pm

@@ -0,0 +1,110 @@
+package DNS::LDNS::DNSSecName;
+
+use 5.008008;
+use strict;
+use warnings;
+
+use DNS::LDNS ':all';
+
+our $VERSION = '0.61';
+
+sub new {
+    my $class = shift;
+    return _new;
+}
+
+sub name {
+    my $self = shift;
+    return DNS::LDNS::GC::own($self->_name, $self);
+}
+
+sub set_name {
+    my ($self, $name) = @_;
+
+    DNS::LDNS::GC::disown(my $old = $self->name);
+    _set_name($self, my $copy = $name->clone);
+    DNS::LDNS::GC::own($copy, $self);
+}
+
+sub rrsets {
+    my $self = shift;
+    return DNS::LDNS::GC::own($self->_rrsets, $self);
+}
+
+sub add_rr {
+    my ($self, $rr) = @_;
+
+    my $s = _add_rr($self, my $copy = $rr->clone);
+    DNS::LDNS::GC::own($copy, $self);
+    $DNS::LDNS::last_status = $s;
+    return $s;
+}
+
+sub nsec {
+    my $self = shift;
+    return DNS::LDNS::GC::own($self->_nsec, $self);
+}
+
+sub set_nsec {
+    my ($self, $nsec) = @_;
+
+    DNS::LDNS::GC::disown(my $old = $self->nsec);
+    _set_nsec($self, my $copy = $nsec->clone);
+    DNS::LDNS::GC::own($copy, $self);
+}
+
+sub hashed_name {
+    my $self = shift;
+    return DNS::LDNS::GC::own($self->_hashed_name, $self);
+}
+
+sub nsec_signatures {
+    my $self = shift;
+    return DNS::LDNS::GC::own($self->_nsec_signatures, $self);
+}
+
+sub DESTROY {
+    DNS::LDNS::GC::free($_[0]);
+}
+
+1;
+__END__
+
+=head1 NAME
+
+DNS::LDNS::DNSSecName - Dname with rrsets in a dnssec zone
+
+=head1 SYNOPSIS
+
+  use LDNS ':all'
+
+  my name = new DNS::LDNS::DNSSecName
+
+  rdata = name->name
+  name->set_name(rdata)
+  bool = name->is_glue
+  rrsets = name->rrsets
+  name->add_rr(rr)
+
+  rr = name->nsec
+  name->set_nsec(rr)
+  hash = name->hashed_name
+  rrs = name->nsec_signatures
+
+=head1 SEE ALSO
+
+http://www.nlnetlabs.nl/projects/ldns
+
+=head1 AUTHOR
+
+Erik Pihl Ostlyngen, E<lt>erik.ostlyngen@uninett.noE<gt>
+
+=head1 COPYRIGHT AND LICENSE
+
+Copyright (C) 2013 by UNINETT Norid AS
+
+This library is free software; you can redistribute it and/or modify
+it under the same terms as Perl itself, either Perl version 5.14.2 or,
+at your option, any later version of Perl 5 you may have available.
+
+=cut