Don't advertise the noop output

include/render.c

@@ -31,3 +31,7 @@ struct wlr_backend *river_wlr_noop_backend_create(struct wl_display *display) {
 struct wlr_output *river_wlr_noop_add_output(struct wlr_backend *backend) {
     return wlr_noop_add_output(backend);
 }
+
+bool river_wlr_output_is_noop(struct wlr_output *output) {
+    return wlr_output_is_noop(output);
+}

include/render.h

@@ -29,5 +29,6 @@ bool river_wlr_backend_is_multi(struct wlr_backend *backend);
 struct wlr_session *river_wlr_backend_get_session(struct wlr_backend *backend);
 struct wlr_backend *river_wlr_noop_backend_create(struct wl_display *display);
 struct wlr_output *river_wlr_noop_add_output(struct wlr_backend *backend);
+bool river_wlr_output_is_noop(struct wlr_output *output);
 
 #endif

src/output.zig

@@ -86,6 +86,7 @@ pub const Output = struct {
         self.listen_mode.notify = handleMode;
         c.wl_signal_add(&wlr_output.events.mode, &self.listen_mode);
 
+        if (!c.river_wlr_output_is_noop(wlr_output)) {
             // Add the new output to the layout. The add_auto function arranges outputs
             // from left-to-right in the order they appear. A more sophisticated
             // compositor would let the user configure the arrangement of outputs in the
@@ -97,6 +98,7 @@ pub const Output = struct {
             // DPI, scale factor, manufacturer, etc).
             c.wlr_output_create_global(wlr_output);
         }
+    }
 
     /// Add a new view to the output. arrangeViews() will be called by the view
     /// when it is mapped.