AC_ARG_WITH(libidn, AC_HELP_STRING([--with-libidn=[DIR]],
[Support IDN/IRIs (needs GNU Libidn)]),
libidn=$withval, libidn="")
AC_ARG_WITH(libidn, AC_HELP_STRING([--with-libidn=[DIR]],
[Support IDN/IRIs (needs GNU Libidn)]),
libidn=$withval, libidn="")