Simplify configure.ac.in by using XDT_VERSION_INIT
Tried to follow xfdesktop!97 (merged), for getting rid of configure.ac.in
preprocessing, but failed for thunarx_version_api
and thunar_debug_default
(I suppose it is required to get rid of all m4_define
to prevent preprocessing ?)
@kelnos, if you have further hints, they would be welcome
I suppose fine to at least push this minor simplification