[gdm] user-switching: fix sd_session_get_uid check

[Ray Strode <halfline src gnome org>]

commit ad7b1851b8d5e1cc5ac9408f931e0b83c9c557c3
Author: Ray Strode <rstrode redhat com>
Date:   Mon Mar 19 14:49:01 2012 -0400

    user-switching: fix sd_session_get_uid check
    
    It returns 0 on success.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=655380

 daemon/gdm-slave.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/daemon/gdm-slave.c b/daemon/gdm-slave.c
index d864a3d..a1fded1 100644
--- a/daemon/gdm-slave.c
+++ b/daemon/gdm-slave.c
@@ -1347,7 +1347,7 @@ gdm_slave_get_primary_session_id_for_user_from_systemd (GdmSlave   *slave,
                         uid_t other;
 
                         res = sd_session_get_uid (sessions[i], &other);
-                        if (res > 0 && other == uid) {
+                        if (res == 0 && other == uid) {
                                 primary_ssid = g_strdup (sessions[i]);
                         }
                 }