The only addition to v4 was `wl_surface_damage_buffer`, which we do not
use.
This change should allow running on more compositors (even though v4 is
already old -- 5 years now).
Ref
3384f69ecf.
The Wayland display server is getting unwieldy due to the sheer size.
To make it easier to edit in the future, I split it into many components
based on logical boundaries.