Security fix, CVE-2017-14492, DHCPv6 RA heap overflow.
    
    Fix heap overflow in IPv6 router advertisement code.
    This is a potentially serious security hole, as a
    crafted RA request can overflow a buffer and crash or
    control dnsmasq. Attacker must be on the local network.
    
    Signed-off-by: Petr Menšík <pemensik@redhat.com>