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/python/file_py3.i

@@ -0,0 +1,121 @@
+/*
+ * file_py3.i: Typemaps for FILE* for Python 3
+ *
+ * Copyright (c) 2011, Karel Slany (karel.slany AT nic.cz)
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ *     * Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the organization nor the names of its
+ *       contributors may be used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+%{
+#include <unistd.h>
+#include <fcntl.h>
+%}
+
+%types(FILE *);
+
+/* converts basic file descriptor flags onto a string */
+%fragment("fdfl_to_str", "header") {
+const char *
+fdfl_to_str(int fdfl) {
+
+  static const char * const file_mode[] = {"w+", "w", "r"};
+
+  if (fdfl & O_RDWR) {
+    return file_mode[0];
+  } else if (fdfl & O_WRONLY) {
+    return file_mode[1];
+  } else {
+    return file_mode[2];
+  }
+}
+}
+
+%fragment("obj_to_file","header", fragment="fdfl_to_str") {
+FILE *
+obj_to_file(PyObject *obj) {
+%#if PY_VERSION_HEX >= 0x03000000
+  int fd, fdfl;
+  FILE *fp;
+  if (!PyLong_Check(obj) &&                                /* is not an integer */
+      PyObject_HasAttrString(obj, "fileno") &&             /* has fileno method */
+      (PyObject_CallMethod(obj, "flush", NULL) != NULL) && /* flush() succeeded */
+      ((fd = PyObject_AsFileDescriptor(obj)) != -1) &&     /* got file descriptor */
+      ((fdfl = fcntl(fd, F_GETFL)) != -1)                  /* got descriptor flags */
+    ) {
+    fp = fdopen(dup(fd), fdfl_to_str(fdfl)); /* the FILE* must be flushed
+                                                and closed after being used */
+#ifdef SWIG_FILE3_DEBUG
+    fprintf(stderr, "opening fd %d (fl %d \"%s\") as FILE %p\n",
+            fd, fdfl, fdfl_to_str(fdfl), (void *)fp);
+#endif
+    return fp;
+  }
+%#endif
+  return NULL;
+}
+}
+
+/* returns -1 if error occurred */
+%fragment("dispose_file", "header") {
+int
+dispose_file(FILE **fp) {
+#ifdef SWIG_FILE3_DEBUG
+  fprintf(stderr, "flushing FILE %p\n", (void *)fp);
+#endif
+  if (*fp == NULL) {
+    return 0;
+  }
+  if ((fflush(*fp) == 0) &&  /* flush file */
+      (fclose(*fp) == 0)) {  /* close file */
+    *fp = NULL;
+    return 0;
+  }
+  return -1;
+}
+}
+
+%typemap(arginit, noblock = 1) FILE* {
+  $1 = NULL;
+}
+
+%typemap(check, noblock = 1) FILE* {
+  if ($1 == NULL) {
+    /* The generated wrapper function raises TypeError on mismatching types. */
+    SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname" "', argument "
+                        "$argnum"" of type '" "$type""'");
+  }
+}
+
+%typemap(in, noblock = 1, fragment = "obj_to_file") FILE* {
+  $1 = obj_to_file($input);
+}
+
+%typemap(freearg, noblock = 1, fragment = "dispose_file") FILE* {
+  if (dispose_file(&$1) == -1) {
+    SWIG_exception_fail(SWIG_IOError, "closing file in method '" "$symname" "', argument "
+                        "$argnum"" of type '" "$type""'");
+  }
+}