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/test/999-compile-nossl.tpkg/999-compile-nossl.dsc

@@ -0,0 +1,14 @@
+BaseName: 999-compile-nossl
+Version: 1.0
+Description: compile ldns without openssl
+CreationDate: Wed Jan 11 11:51:50 CET 2006
+Maintainer: Miek Gieben
+Category: 
+Component:
+Depends: 
+Pre: 
+Post:
+Test: 999-compile-nossl.test
+AuxFiles: 
+Passed:
+Failure:

zonemaster-ldns/ldns/test/999-compile-nossl.tpkg/999-compile-nossl.help

@@ -0,0 +1,4 @@
+Synopsis: tpkg  -a ../../ exe 01-compile.tpkg
+-a path: path is where the source lives
+as the test is executed in it own subsdir it will
+need ../../ is you use a relative path

zonemaster-ldns/ldns/test/999-compile-nossl.tpkg/999-compile-nossl.test

@@ -0,0 +1,43 @@
+[ -f ../.tpkg.var.master ] && source ../.tpkg.var.master
+
+export PATH=$PATH:/usr/sbin:/sbin:/usr/local/bin:/usr/local/sbin:.
+
+# first arg is the build dir
+TPKG_BUILD=$1
+
+cd $TPKG_BUILD
+ORIGDIR=`pwd`
+
+case $OSTYPE in
+        linux*)
+		TMP=`mktemp -d`
+                libtoolize && autoreconf && \
+		cd $TMP && \
+                $ORIGDIR/configure --without-ssl && \
+                make
+        ;;
+        freebsd*)
+		TMP=`mktemp -t /tmp -d`
+                libtoolize && \
+                autoconf259 && autoheader259 && \
+		cd $TMP && \
+                $ORIGDIR//configure --without-ssl && \
+                gmake
+        ;;
+        darwin*)
+		TMP=`mktemp -d`
+                glibtoolize && \
+                autoconf && autoheader && \
+		export MACOSX_DEPLOYMENT_TARGET=10.4 && \
+		cd $TMP && \
+                $ORIGDIR//configure --without-ssl && \
+                make
+        ;;
+esac
+
+cd $ORIGDIR
+RES=$?
+echo "DIR:"
+echo $TMP
+rm -rf $TMP
+exit $RES