configure: two fixes on dependencies

1) netsniff-ng is also dependant on libnl (e.g. for raw 802.11 devices)
2) Only netsniff-ng depends on tpacket_v3, trafgen on tpacket_v2. Thus,
   add checks for both.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
configure: test also tpacket flags e.g. used in TX_RING

Also try compile-testing TPACKET_V2/3 flags that are used in some
particular versions, especially in TX_RING.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>