osc.lua: fix window controls not showing in fullscreen

Author: kasper93

player/lua/osc.lua

@@ -650,7 +650,7 @@ end
 local function window_controls_enabled()
     local val = user_opts.windowcontrols
     if val == "auto" then
-        return not (state.border and state.title_bar)
+        return state.fullscreen or not state.border or not state.title_bar
     else
         return val ~= "no"
     end