[gnome-session] autostart: don't set DISPLAY in autostarted apps for wayland sessions

[Ray Strode <halfline src gnome org>]

commit c3c3f2b97897784d6268653cb1d46d29688ac3bd
Author: Ray Strode <rstrode redhat com>
Date:   Wed Dec 17 15:14:05 2014 -0500

    autostart: don't set DISPLAY in autostarted apps for wayland sessions
    
    DISPLAY is an X11-ism, and is unset for wayland.  This was leading to
    log spew.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741679

 gnome-session/gsm-autostart-app.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/gnome-session/gsm-autostart-app.c b/gnome-session/gsm-autostart-app.c
index 1de4eed..75008fe 100644
--- a/gnome-session/gsm-autostart-app.c
+++ b/gnome-session/gsm-autostart-app.c
@@ -1032,8 +1032,14 @@ autostart_app_start_spawn (GsmAutostartApp *app,
         g_free (app->priv->startup_id);
         local_error = NULL;
         ctx = g_app_launch_context_new ();
-        g_app_launch_context_setenv (ctx, "DISPLAY", g_getenv ("DISPLAY"));
-        g_app_launch_context_setenv (ctx, "DESKTOP_AUTOSTART_ID", startup_id);
+
+        if (g_getenv ("DISPLAY") != NULL) {
+                g_app_launch_context_setenv (ctx, "DISPLAY", g_getenv ("DISPLAY"));
+        }
+
+        if (startup_id != NULL) {
+                g_app_launch_context_setenv (ctx, "DESKTOP_AUTOSTART_ID", startup_id);
+        }
 
         handler = g_signal_connect (ctx, "launched", G_CALLBACK (app_launched), app);
         success = g_desktop_app_info_launch_uris_as_manager (app->priv->app_info,