[master] b016f662c build: Bump autotools dependencies to ancient versions

[Dridi Boukelmoune]

commit b016f662c86cbee67846ecb553403bea11f64d6e
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Thu Sep 9 18:56:12 2021 +0200

    build: Bump autotools dependencies to ancient versions
    
    The previous ones were antiquated.

diff --git a/autogen.des b/autogen.des
index 7fffce8c3..294053b87 100755
--- a/autogen.des
+++ b/autogen.des
@@ -25,10 +25,6 @@ fi
 rm -f $SRCDIR/configure
 autoreconf -i -v $SRCDIR
 
-# autoconf prior to 2.62 has issues with zsh 4.2 and newer
-CONFIG_SHELL=/bin/sh
-export CONFIG_SHELL
-
 # NB: Workaround for make distcheck not working with
 # NB: FreeBSD's make on -current
 # env MAKE=gmake \
diff --git a/configure.ac b/configure.ac
index 513bf9fbe..eb055da0a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-AC_PREREQ(2.59)
+AC_PREREQ(2.69)
 AC_COPYRIGHT([Copyright (c) 2006 Verdens Gang AS
 Copyright (c) 2006-2021 Varnish Software])
 AC_REVISION([$Id$])
@@ -19,7 +19,7 @@ AC_CANONICAL_SYSTEM
 AC_LANG(C)
 
 AM_MAINTAINER_MODE([disable])
-AM_INIT_AUTOMAKE([1.11 foreign color-tests parallel-tests subdir-objects])
+AM_INIT_AUTOMAKE([1.13 foreign color-tests parallel-tests subdir-objects])
 AM_EXTRA_RECURSIVE_TARGETS([recheck])
 AM_SILENT_RULES([yes])
 AC_DISABLE_STATIC
diff --git a/doc/sphinx/whats-new/upgrading-trunk.rst b/doc/sphinx/whats-new/upgrading-trunk.rst
index 470271060..c2c3350cf 100644
--- a/doc/sphinx/whats-new/upgrading-trunk.rst
+++ b/doc/sphinx/whats-new/upgrading-trunk.rst
@@ -160,6 +160,10 @@ Changes for developers
 Build
 -----
 
+Building from source requires autoconf 2.69 or newer and automake 1.13 or
+newer. Neither are needed when building from a release archive since they
+are already bootstrapped.
+
 There is a new ``--enable-workspace-emulator`` configure flag to replace the
 regular "packed allocation" workspace with a "sparse allocation" alternative.
 Combined with the Address Sanitizer it can help VMOD authors find memory