Rework SMF support in preparation for integration.

 - Properly abstract the choice between different init styles with
   INIT_SERVICE.  Set default to 'smf' on SunOS >= 5.10, otherwise
   default to 'rc.d'.

 - Handle PLIST entries dynamically and hide them from print-PLIST
   generation.

 - Source SMF manifest and method files from FILESDIR.

 - Remove unnecessary parts of smf.mk

 - Add dependency to post-install target rather than defining our
   own stage.

 - Clean up the install messages to be similar to others.
Remove SMF_USER SMF_GROUP and SMF_HOME.

We will re-use per-package variables for substituting variables in SMF
scripts as they will already be used in rc.d scripts.
SMF conversion for security/clamav.