Custom wlr_client_buffer from wl_resource
Created by: bl4ckb0ne
This patch is a rewrite of the work done by ddevault in https://github.com/swaywm/wlroots/commit/c88abfbc23da485507add71534785b4d8141efdc
The patchset is currently used here in my own fork of wxrc.
I chose to not make the existing client buffer impl (shm, dma-buf and wl_drm) yet because of the pending status of wl_drm in wlroots.