pkt_buff: Remove unnecessary void cast

lookup_hash() returns void * which does not need to be cast.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
proto: Remove unnecessary include of hash.h

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
dissector: Get rid of now unnecessary HAVE_DISSECTOR_PROTOS

Since commit 1cc762a ("lookup: Move UDP/TCP port and Ethernet type
lookup into own module") the netsniff-ng tool is the only one using the
dissector infrastructure. Thus we no longer need to conditionally device
HAVE_DISSECTOR_PROTOS, since netsniff-ng is the only tool defining this.

While at it, also remove the __WITH_PROTOS macro which is checked in
dissector_init_ethernet/dissector_cleanup_ethernet but is defined
nowhere. This will cause the functions to be called from both the
ethernet and ieee80211 dissectors, thus make sure we check the
initialization state before freeing as well.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>