Log Message:
x11/compton: Switch upstream to the same fork as Arch Linux, update to 4.0.

Take maintainership.

Notable changes (no changelog is available):

* [pkgsrc] Some dependencies made into options.
* The paint-on-overlay configuration option was removed, and is now enabled
by default.
* The xrender-sync and xrender-sync-fence options were removed.
* Moved most of the X functions (XShape, XComposite, Xrender, Xinerama, etc.)
to xcb.
* Moved from server side region (Xfixes) to client side (pixman).
* Use libev for I/O and timeout events.