+AC_ARG_WITH(system-libltdl,
+[ --with-system-libltdl Use the libltdl installed in your system (default=use our own)],
+[
+LIBLTDL="-lltdl"
+INCLTDL=
+LTDL_SUBDIRS=
+enable_ltdl_install=no
+],
+[
+dnl If libltdl isn't installable, set it to be installable.
+[test x"$enable_ltdl_install" = x && enable_ltdl_install=yes]