define the _XOPEN_SOURCE define in the config.h file instead, and also added a

  mips-sgi-irix*)

    if test "$GCC" != "yes"; then

      xopen="yes"

      CPPFLAGS="$CPPFLAGS -D_XOPEN_SOURCE=500"

      # "Applications should ensure that the feature test macro _XOPEN_SOURCE

      # is defined with the value 500 before inclusion of any header. This is

      # needed to enable the functionality described in this specification,

      # and possibly to enable functionality defined elsewhere in the Common

      # Applications Environment."

      # So far, we've only detected this to be strictly necessary if not using

      # gcc on SGI IRIX. And this only to avoid warnings.

      AC_DEFINE(_XOPEN_SOURCE, 500, [ensure SUSV2 compatibility])

    fi

    ;;

  *)