Add SMF support.

 - Introduce smf.mk to handle SMF - Service Management Facility.

 - 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.  Remove rc.d entries from PLISTs.

 - Source SMF manifest and method files from FILESDIR and import SMF
   bits for a number of packages.