AC_DEFUN([DX_FEATURE_pdf], ON)
AC_DEFUN([DX_FEATURE_ps], ON)
+# Compatibility with older autoconf versions.
+m4_ifdef([AS_HELP_STRING], , [m4_define([AS_HELP_STRING], m4_defn([AC_HELP_STRING]))])
+
## --------------- ##
## Private macros. ##
## --------------- ##