This skips over xdg-shell v4, which can be implemented with no changes
as it's just another optional event.
v5 adds a capabilities event, which we send to inform clients of the
window manager's capabilities.
Signed-off-by: Daniel Stone <daniels@collabora.com>
It's not really useful to have libweston without libweston-desktop. It's
also very little code.
Merging both into the same DSO will allow us to cut out a bunch of
indirection and pain.
Signed-off-by: Daniel Stone <daniels@collabora.com>