Have autogen.sh fail if autoreconf fails

If the autoreconf program does not succeed, autogen.sh
should not succeed either.

The definition of "succeed" being "exit with exit code 0".

autogen.sh

@@ -6,9 +6,11 @@ if autoreconf --install --symlink --force; then
 	echo "------------------------------------------------------"
 	echo
 else
+	s="$?"
 	echo
 	echo "--------------------------"
 	echo "Running autoreconf failed."
 	echo "--------------------------"
 	echo
+	exit "$s"
 fi