Move from exo-csource to xdt-csource
## Submitted by Skunnyk `@skunnyk`
Assigned to **Skunnyk `@skunnyk`**
**[Link to original bug (#16717)](https://bugzilla.xfce.org/show_bug.cgi?id=16717)**
## Description
Followiing [bug 6449](https://bugzilla.xfce.org/show_bug.cgi?id=6449), we need to finish the transition from exo-csource to xdt-csource.
exo-csource have been merged in xdt-csource in 4.14
This way, we don't need to depend on exo on build time when not needed.
Version: git
issue