[gdm] manager: avoid leaking session_id

[Ray Strode <halfline src gnome org>]

commit a7f210d81cecaf3ddb89605b89dfadea8c4102e9
Author: Lubomir Rintel <lkundrak v3 sk>
Date:   Mon Jun 18 12:33:42 2018 +0200

    manager: avoid leaking session_id
    
    get_login_window_session_id() duplicates the session id.

 daemon/gdm-manager.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/daemon/gdm-manager.c b/daemon/gdm-manager.c
index 7539acf1..b4f01922 100644
--- a/daemon/gdm-manager.c
+++ b/daemon/gdm-manager.c
@@ -1414,6 +1414,7 @@ activate_login_window_session_on_seat (GdmManager *self,
         }
 
         activate_session_id (self, seat_id, session_id);
+        g_free (session_id);
 }
 
 static void