For development to continue on systems (such as optimus laptops) that
have multiple GPUs, we need a way to reference all of the renderers
that have been created for devices in the system. A wlr_multi_gpu
struct holds renderers coming from two different sources:
1. the primary renderer (given to us by the compositor)
2. drm sub backends, each of which has a renderer created for
cross-GPU copies.
This change provides a way to access all of these from the same
place.
This introduces -DWLR_USE_UNSTABLE and adds information regarding the
stability status to all headers. I started with a conservative set of
headers to mark as stable:
- types/wlr_matrix.h
- util/edges.h
- util/log.h
- util/region.h
- xcursor.h