package/wlroots: new package

wlroots is a modular library which provides building blocks to
implement Wayland compositors. wlroots is a dependency of the
Cage Wayland compositor.

https://github.com/swaywm/wlroots/



Signed-off-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>