The variable that control IDN enablement is called USE_IDN within these
Makefiles
# | (__| |_| | _ <| |___
# \___|\___/|_| \_\_____|
#
-# Copyright (C) 1999 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+# Copyright (C) 1999 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
USE_IPV6=true
!ENDIF
-!IFNDEF ENABLE_IDN
+!IFNDEF USE_IDN
USE_IDN =true
!ELSEIF "$(USE_IDN)"=="yes"
USE_IDN =true