Keep stacking order across restarts

ReparentWindow puts the window at the top of the stacking order. Thus, we have
to reparent clients back to the root window in the stacking order.

Signed-off-by: Uli Schlachter <psychon@znc.in>

awesome.c

@@ -72,8 +72,8 @@ awesome_atexit(bool restart)
     lua_pushboolean(globalconf.L, restart);
     signal_object_emit(globalconf.L, &global_signals, "exit", 1);
 
-    /* Move clients where we want them to be */
-    foreach(c, globalconf.clients)
+    /* Move clients where we want them to be and keep the stacking order intact */
+    foreach(c, globalconf.stack)
     {
         xcb_reparent_window(globalconf.connection, (*c)->window, globalconf.screen->root,
                 (*c)->geometry.x, (*c)->geometry.y);