action handling: define and use macros

The action field in Packet structure should not be accessed
directly as the tunneled packet needs to update the root packet
and not the initial packet.

This patch is fixing issue #819 where suricata was not able to
drop fragmented packets in AF_PACKET IPS mode. It also fixes
drop capability for tunneled packets.
action handling: use macro for test.

Use test macro instead of direct access to action field.

This patch has been obtained by using the following
spatch file:

  @@
  Packet *p;
  expression E;
  @@

  - p->action & E
  + TEST_PACKET_ACTION(p, E)
action handling: add test to avoid direct access

Direct access to the action field of Packet structure is not
allowed.