Prepare for pf 3.5 import:

Prepare for pf 3.5 import:
 - Remove pflog and pfsync modules. Things will change in such a fashion
   that there will be one module with pf+pflog that can be loaded into
   GENERIC without problems (which is what most people want). pfsync is no
   longer possible as a module.
 - Add multicast address for in-kernel multicast pfsync protocol. Protocol
   glue will follow once the import is done.
 - Add one more mbuf tag