package_daemon: Cleanups.

- Remove no longer needed context object, as well as dummy
  BDecisionProvider implementation, as the base class now does the same
  directly by default.
Clean up FreeBSD build support as suggested by Ingo.
Drop the together keyword on the Clean action

Since the PM merge we now have way too many targets,
here jam clean just fails in execve() due to too long arguments.

jam clean is now very verbose but at least it works.

Another option could be to override the Clean rule itself
to clean in batch by splitting the list...
Patches welcome.
Add definitions for M68K repositories and package infos