Adding a framebuffer with the given modifiers fails for some reason. Forcing
the gbm surface to linear is one workaround, but instead
let's use the old API without modifiers but still planar support.
This also removes the dependency to drm-ffi again, which was missing from renderer-femtovg.
The cursor is loaded by the window adapter from the cache. When it's
loaded the first time, its format will be Svg, so we convert it to a
pixel buffer. That way the skia backend can convert it on first draw
into a skia_safe::Image and replace the cache entry with the backend
storage variant.
This doesn't require a windowing system, just Linux and Vulkan drivers
that supports the display extensions.
It's called linuxkms as soon this will go beyond Vulkan and also support
EGL and perhaps dumb buffers for software rendering.
