xwayland: Pass MetaWaylandCompositor pointer when initializing

This way we can initialize without having any way to retrieve it via
some global variable. This isn't needed now, but will be once Wayland
infrastructure initializiation is done in a single step.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1863>

src/wayland/meta-wayland.c

@@ -558,6 +558,7 @@ meta_wayland_compositor_setup (MetaWaylandCompositor *compositor)
       g_autoptr (GError) error = NULL;
 
       if (!meta_xwayland_init (&compositor->xwayland_manager,
+                               compositor,
                                compositor->wayland_display,
                                &error))
         g_error ("Failed to start X Wayland: %s", error->message);

src/wayland/meta-xwayland-private.h

@@ -26,6 +26,7 @@
 
 gboolean
 meta_xwayland_init (MetaXWaylandManager    *manager,
+                    MetaWaylandCompositor  *compositor,
                     struct wl_display      *display,
                     GError                **error);
 

src/wayland/meta-xwayland.c

@@ -568,6 +568,7 @@ xserver_died (GObject      *source,
         meta_display_shutdown_x11 (display);
 
       if (!meta_xwayland_init (&compositor->xwayland_manager,
+                               compositor,
                                compositor->wayland_display,
                                &error))
         g_warning ("Failed to init X sockets: %s", error->message);
@@ -1138,6 +1139,7 @@ meta_xwayland_stop_xserver (MetaXWaylandManager *manager)
 
 gboolean
 meta_xwayland_init (MetaXWaylandManager    *manager,
+                    MetaWaylandCompositor  *compositor,
                     struct wl_display      *wl_display,
                     GError                **error)
 {