notify_key: Add update_state argument

notify_key: Add update_state argument

If update_state is true, then notify_key will continue to call
xkb_key_update_state to update the local state mask, as before this
commit.  Otherwise, it will rely on the compositor to manually update
the state itself, for nested compositors.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>