backend-pipewire: add GL renderer support
Allow to use the GL renderer instead of pixman to render the PipeWire output of the PipeWire backend.
The renderer may be selected using the --renderer=gl
option on the command-line.
weston --socket=wayland-pipewire --backend=pipewire --renderer=gl
Marked as draft, as the merge request depends on !1263 (merged). This is needed for reading the framebuffer of the renderer into the PipeWire buffers.
Edited by Michael Tretter