AC_DEFUN_ONCE([AC_CONFIG_SUBDIRS_OPTIONAL],
 [
 AC_REQUIRE([AC_CONFIG_SUBDIRS])
 subdirfailed=no
 AC_CONFIG_SUBDIRS([$1])
 m4_define([_AC_OUTPUT_SUBDIRS],
 	  [
        	  m4_pushdef([AC_MSG_ERROR],[subdirfailed=yes])
 	  ]m4_defn([_AC_OUTPUT_SUBDIRS])[
 	  m4_popdef([AC_MSG_ERROR])])

 ])