Don't manually unban all windows on exit

The last commit made sure the X server does this for us instead. No need to do
that work twice.

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

awesome.c

@@ -76,10 +76,6 @@ awesome_atexit(void)
         screen_nbr++)
         systray_cleanup(screen_nbr);
 
-    /* remap all clients since some WM won't handle them otherwise */
-    foreach(c, globalconf.clients)
-        client_unban(*c);
-
     /* Close Lua */
     lua_close(globalconf.L);