Work around autoconf 2.69 bugs

autogen.sh

@@ -6,3 +6,20 @@
 # Requires GNU autoconf, GNU automake and GNU libtool.
 #
 autoreconf -vif `dirname "$0"`
+
+# autoconf 2.69 has a bug where autoreconf does not copy config.guess
+# and config.sub even though configure.ac needs them, unless automake is
+# being used. We work around this by forcing a call to automake if one
+# or both of config.sub and config.guess are missing.
+if ! test -x config.guess -a -x config.sub ; then
+  automake -acf 2> /dev/null || :
+fi
+
+# There is a second bug in autoconf 2.69 where the generated configure
+# script complains about install-sh not being there (even though it does
+# not actually need it). As a workaround, we just provide an empty file
+# instead. Since newer autoconf versions such as 2.71 are not affected
+# by the bug, we add a test to limit when this workaround is applied
+if fgrep -q ac_aux_dir/install-sh configure ; then
+  touch install-sh
+fi