Since we only use the backend capabilities here we can simply pass
them in directly. This allows other locations to create an allocator
even if they don't have a backend. They can simply specify the caps
they want instead.
Replace them with wlr_signal_emit_safe, which correctly handles
cases where a listener removes another listener.
Reported-by: Isaac Freund <ifreund@ifreund.xyz>
Now that the DRM backend no longer depends on GBM, we can make it
optional. The GLES2 renderer still depends on it because of our EGL
device selection.
This is useful for compositors with their own renderers, and for
compositors using the Vulkan renderer.
If the backend doesn't have a DRM FD, fallback to the renderer's.
This accomodates for the situation where the headless backend hasn't
picked a DRM FD in particular, but the renderer has picked one.
If we aren't trying to create a dumb buffer allocator, and if the
DRM device has a render node (ie, not a split render/display SoC),
then we can use the render node instead of the primary node. This
should allow wlroots to run under seatd when the current user
doesn't have the permission to open primary nodes (logind has a
quirk to allow physically logged in users to open primary nodes).
