Introducing SMF support

[Jonathan Perkin <jperkin%joyent.com@localhost>]

For a while Joyent have had SMF support in pkgsrc thanks to Filip's
initial work.  SMF is the native init system in Solaris 10 and newer,
and many of our packages have the necessary support.

It's time we integrated this work, so I've cleaned it up a bit and
tried to make it a bit more generic, so that Linux folks can at some
point easily add support for systemd/upstart/whatever, or OSX can grow
launchd support, etc.

The infrastructure changes, along with a conversion of the clamav
package, are here:

  
https://github.com/joyent/pkgsrc/compare/trunk...joyent/feature/smf/trunk#files_bucket

To summarise the changes necessary:

  - Add user-settable INIT_SYSTEM variable, with the user able to
    choose between 'rc.d' and 'smf'.  Once the majority of packages
    have been converted to support SMF, we will make the default 'smf'
    on SunOS >= 5.10.  Default otherwise will remain 'rc.d'.

  - Make PLIST generation of rc.d/smf scripts dynamic.  This will
    entail removing the 'share/examples/rc.d' entries from all PLISTs
    but will allow either system to be used without PLIST vars.

  - Import an SMF 'manifest.xml' file, and an optional 'method' file,
    into ${FILESDIR}/smf for each supporting package.

The hooks into existing mk/ files are minimal, but please let me know
if there are cleaner ways of doing them, especially the
_INSTALL_RCD_SCRIPTS changes.

I would like to integrate this before 2013Q3, so please raise any
concerns as soon as possible.

Thanks,

-- 
Jonathan Perkin  -  Joyent, Inc.  -  www.joyent.com