src/bin/dhcp4/dhcp4_messages.mes
    Added DHCP4_PACKET_DROP_0009 for possible bootp packets

src/bin/dhcp4/dhcp4_srv.cc
    Dhcpv4Srv::acceptMessageType()
        rearranged a bit to test explicitly for DHCP_NOTYPE

src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
    TEST_F(Dhcpv4SrvTest, acceptMessageType)
    Added tests for packets with no option 53 and for
    type > DHCPLEASEQUERYDONE