Fix privilege enforcement being useless

Privilege violations caused an error message but didn't abort the operation

advtrains/advtrains_luaautomation/active_common.lua

@@ -58,6 +58,7 @@ end
 function ac.on_receive_fields(pos, formname, fields, player)
 	if not minetest.check_player_privs(player:get_player_name(), {atlatc=true}) then
 		minetest.chat_send_player(player:get_player_name(), "Missing privilege: atlatc - Operation cancelled!")
+		return
 	end
 	
 	local meta=minetest.get_meta(pos)

advtrains/advtrains_luaautomation/pcnaming.lua

@@ -30,6 +30,7 @@ minetest.register_craftitem("advtrains_luaautomation:pcnaming",{
 		end
 		if not minetest.check_player_privs(pname, {atlatc=true}) then
 			minetest.chat_send_player(pname, "Missing privilege: atlatc")
+			return
 		end
 		if pointed_thing.type=="node" then
 			local pos=pointed_thing.under