Log Message:
It seems that when kqueue was merged to the trunk, sys/select.h
was altered to include sys/queue.h, which supplies a pile of macros
and defines _SYS_QUEUE_H_.  Prior to this change, ettercap was able
to pull in its own ec_queue.h file to define these macros (and the
missing ones below) and also define _SYS_QUEUE_H_.  The two macros
listed below are not in our definition of the macros, so we define
them manually later, if they're not defined by the include files.