Simplify configure.ac.in by using XDT_VERSION_INIT

Followup of MR !335

configure.ac.in

@@ -31,11 +31,11 @@ dnl ***************************
 dnl *** Initialize autoconf ***
 dnl ***************************
 AC_COPYRIGHT([Copyright (c) 2004-2022 The Thunar development team. All rights reserved.])
-AC_INIT([thunar], [thunar_version], [https://gitlab.xfce.org/xfce/thunar], [thunar])
+AC_INIT([thunar], [xdt_version], [https://gitlab.xfce.org/xfce/thunar], [thunar])
 AC_PREREQ([2.60])
 AC_CONFIG_MACRO_DIRS([m4])
 AC_CANONICAL_TARGET()
-AC_REVISION([thunar_version_build])
+AC_REVISION([xdt_version_build])
 
 dnl ***************************
 dnl *** Initialize automake ***