[libpng16] Check libtool/libtoolize version number (2.4.2) in configure.ac
diff --git a/configure.ac b/configure.ac
index 028b311..8f6507b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,16 +14,21 @@
dnl This is here to prevent earlier autoconf from being used, it
dnl should not be necessary to regenerate configure if the time
dnl stamps are correct
-AC_PREREQ([2.59])
+AC_PREREQ([2.68])
dnl Version number stuff here:
-AC_INIT([libpng],[1.6.0beta08], [png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.0beta08],[png-mng-implement@lists.sourceforge.net])
AC_CONFIG_MACRO_DIR([scripts])
AM_INIT_AUTOMAKE
-dnl stop configure from automagically running automake
AM_MAINTAINER_MODE
+dnl configure.ac and Makefile.am expect automake 1.11.2 or a compatible later
+dnl version; aclocal.m4 will generate a failure if you use a prior version of
+dnl automake, so the following is not necessary (and is not defined anyway):
+dnl AM_PREREQ([1.11.2])
+dnl stop configure from automagically running automake
+
PNGLIB_VERSION=1.6.0beta08
PNGLIB_MAJOR=1
PNGLIB_MINOR=6
@@ -45,7 +50,11 @@
AC_PROG_INSTALL
AC_PROG_LN_S
AC_PROG_MAKE_SET
+
+dnl libtool/libtoolize; version 2.4.2 is the tested version, this or any
+dnl compatible later version may be used
LT_INIT([win32-dll])
+LT_PREREQ([2.4.2])
# On Solaris 10 and 12 CPP gets set to cc -E, however this still
# does some input parsing. We need strict ANSI-C style tokenization,