Rename weston_compositor_xkb_init to weston_compositor_set_xkb_rule_names

weston_compositor_xkb_destroy() is called automatically so having only
weston_compositor_xkb_init() to be called by the user was a bit weird.
So rename it so that it makes more sense.
Also export it, since libweston compositors need to call it.

Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor.h b/src/compositor.h
index 0bbf458..c19f991 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -1537,8 +1537,8 @@
 void
 weston_seat_release(struct weston_seat *seat);
 int
-weston_compositor_xkb_init(struct weston_compositor *ec,
-			   struct xkb_rule_names *names);
+weston_compositor_set_xkb_rule_names(struct weston_compositor *ec,
+				     struct xkb_rule_names *names);
 void
 weston_compositor_xkb_destroy(struct weston_compositor *ec);