Add autocompletion for RenderingServer's global shader & has_os_feature

servers/rendering_server.h

@@ -1639,6 +1639,10 @@ public:
 
 	virtual void call_on_render_thread(const Callable &p_callable) = 0;
 
+#ifdef TOOLS_ENABLED
+	virtual void get_argument_options(const StringName &p_function, int p_idx, List<String> *r_options) const override;
+#endif
+
 	RenderingServer();
 	virtual ~RenderingServer();