screencopy-v1: stop using wlr_client_buffer
screencopy-v1: stop using wlr_client_buffer

We can just use the wlr_dmabuf_v1_buffer directly, no need to wrap
it in a wlr_client_buffer.

SirCmpwn/wlroots,swaywm/wlroots,swaywm/wlroots