eve/fivetuple: use intermediate address struct (jsonbuilder prep)

eve/fivetuple: use intermediate address struct (jsonbuilder prep)

Currently alert logging relies on the ability to change existing
values in the json_t structure to overwrite addresses with xff
data. This feature is also used for the "target" logging.

As we can't do this with JsonBuilder, create a new struct to
hold the 5 tuple, with the values swapped as needed, and
overwritten with XFF data if needed. This struct will now
be used to write out the 5 tuple, as well as cache the information
for log fields to be written out later on in the log path.