We only need to damage the parts of the screen that changed since last frame,
we don't need to accumulate damage from previous buffers.
We still need to re-render the accumulated damage.
Fixes https://github.com/swaywm/wlroots/issues/1665
wlr_output_damage_make_current has been renamed to
wlr_output_damage_attach_render, since it's just a wrapper for
wlr_output_attach_render.
wlr_output_damage_swap_buffers has been removed completely. Instead,
wlr_output_damage now listens to successful wlr_output commits and updates its
internal state accordingly.
Simon Ser