dnl @synopsis AC_DEFINE_DIR(VARNAME, DIR [, DESCRIPTION])
dnl
dnl This macro sets VARNAME to the expansion of the DIR variable,
dnl taking care of fixing up ${prefix} and such.
dnl
dnl VARNAME is then offered as both an output variable and a C
dnl preprocessor symbol.
dnl
dnl Example:
dnl
dnl    AC_DEFINE_DIR([DATADIR], [datadir], [Where data are placed to.])
dnl
dnl @category Misc
dnl @author Stepan Kasal <kasal@ucw.cz>
dnl @author Andreas Schwab <schwab@suse.de>
dnl @author Guido U. Draheim <guidod@gmx.de>
dnl @author Alexandre Oliva
dnl @version 2006-10-13
dnl @license AllPermissive

AC_DEFUN([AC_DEFINE_DIR], [
  prefix_NONE=
  exec_prefix_NONE=
  test "x$prefix" = xNONE && prefix_NONE=yes && prefix=$ac_default_prefix
  test "x$exec_prefix" = xNONE && exec_prefix_NONE=yes && exec_prefix=$prefix
dnl In Autoconf 2.60, ${datadir} refers to ${datarootdir}, which in turn
dnl refers to ${prefix}.  Thus we have to use `eval' twice.
  eval ac_define_dir="\"[$]$2\""
  eval ac_define_dir="\"$ac_define_dir\""
  AC_SUBST($1, "$ac_define_dir")
  AC_DEFINE_UNQUOTED($1, "$ac_define_dir", [$3])
  test "$prefix_NONE" && prefix=NONE
  test "$exec_prefix_NONE" && exec_prefix=NONE
])