Log Message:
* Only include bdb.buildlink3.mk if we are using DB[34] as a storage
  driver backend.

* Convert to use bsd.options.mk.  DSPAM_DELIVERY_AGENT_ARGS has been
  deprecated -- just set DSPAM_DELIVERY_AGENT to the LDA instead of
  "custom".

* Only install the documentation for the storage driver used by DSPAM.

* Drop the default signature lifetime from 15 days to 14 days to match
  the DSPAM defaults.

Bump the PKGREVISION to 2.