Require Libtool 2.4.6 and Autoconf 2.69.

configure.ac

 #  Process this file with autoconf to produce a configure script.
 #
-#  automake 1.14
-#  autoconf 2.68
-#  libtool  2.4.2
+#  automake 1.16.1
+#  autoconf 2.69
+#  libtool  2.4.6
+
+AC_PREREQ([2.69])
+LT_PREREQ([2.4.6])
 
 AC_INIT([cdi], [1.9.6rc2], [http://mpimet.mpg.de/cdi])
 

patch/ltmain_sh.patch

 diff --git a/config/ltmain.sh b/config/ltmain.sh
-index 857338f..c19bbcc 100644
+index 0f0a2da..4126a5b 100644
 --- a/config/ltmain.sh
 +++ b/config/ltmain.sh
-@@ -8078,6 +8078,14 @@ func_mode_link ()
+@@ -7859,6 +7859,14 @@ func_mode_link ()
  	# Read the .la file
  	func_source "$lib"