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/tpkg/ChangeLog

@@ -0,0 +1,81 @@
+8 December 2006: Wouter Wijngaards: 1.12
+	* More portable way to extract info from desc files, using 
+	  grep and sed, instead of awk IFS/-F.
+
+3 August 2006: Wouter Wijngaards: 1.11
+	* tar usage more portable.
+	* Multiple tests in Depends: possible.
+	* Usage of tar and awk more portable.
+
+25 Apr 2006: Miek Gieben: 1.10
+	* Allow tpkg report to work again
+	* Base all operations on tar (for speed)
+	* Make tar work on the open
+	* list/extract/etc work again. they call tpkg extract now
+	* cleandir target added, clear *.dir directories
+
+05 Apr 2006: Miek Gieben: 1.07
+	* Added -p priorty for the logging
+	* Always add return code to result file
+	* Add default action: exe when none is given
+
+04 Apr 2006: Miek Gieben: 1.06
+	* Added: CmdDepends: [cmd], [cmd]
+	* Solaris support was added/tested
+	* -k now also works for execute: don't delete the tmp. directory.
+	* post-commit handles branches/tags and trunk, although prob. 
+	  not combined.
+	* Added -n NUM switch, to influence tpkg report's exit code
+	* When cloning rename the testfiles mentioned in the files too
+	* Add pre/post output to the output of tpkg report
+	* Add logging to syslog -l "mesg"
+
+08 Nov 2005: Miek Gieben: 1.05
+	* Various little updates that make 'tpkg' complete
+
+31 Oct 2005: Miek Gieben: 1.04
+	* When a test fails show the result log in "tpkg report"
+	* When running with -q don't show succeses
+
+31 Oct 2005: Miek Gieben: 1.03
+	* Added status line for tpkg report
+	* Cleanup documentation to match .tkpg.var.master
+	  and .tpkg.var.test
+
+28 Oct 2005: Miek Gieben: 1.02
+	* svnserve doesn't set USERNAME nor LOGNAME, add this
+	  to the post-commit script
+	* create post and pre file when target is tmpl - 
+	  stuff them with stuff handy when running from svn(serve)
+	* -q now only prints the errors
+	* Use a new system to convey information between the tests
+	  and scripts; .tpkg.var.master sets up stuff each test
+	  must know. Tests use a .tpkg.var.test file in their
+	  local directory to pass info from .pre to .test to .post
+	* Allow shorter targets -> exe -> e, extract -> ext, etc.
+
+27 Oct 2005: Miek Gieben: 1.01
+	* Added -q flag
+	* Don't abort when a pre/post script fails, but
+	  continue the test and hope it writes a result file
+ 	* Updated the manual and docs
+	* Updated the post-commit hook script
+
+27 Oct 2005: Miek Gieben: 1.00
+	* Added help file and updated documentation
+	* When cloning update the date in the new test
+	* Consistency of the .dsc is checked
+	* -k now works, also when cloning
+	* Abort on unknown options
+	* Some updates to the layout of the tpkg script
+
+26 Oct 2005: Miek Gieben: 0.90
+	* Tagged this release
+
+26 Oct 2005: Miek Gieben: 0.82
+	* Made tpkg clone more robust
+	* Reversed the tpkg report order make PASSED/FAILED standout more
+
+26 Oct 2005: Miek Gieben: 0.81 (not tagged)
+	* Added -k option for tpkg create, which doesn't remove the test.dir/
+	* Documentation updates