add null check of dnsmasq in policy:system
add null check of dnsmasq in policy:system

MelvinTo/firewalla,firewalla/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,firewalla/firewalla,MelvinTo/firewalla,firewalla/firewalla,firewalla/firewalla,MelvinTo/firewalla,firewalla/firewalla