pfsync also depends on pf to be initialized already so pf goes at
FIRST and the interfaces go at ANY.
Then the (VNET_)SYSINIT startups for pf stays at SI_SUB_PROTO_BEGIN
and for pfsync we move to the later SI_SUB_PROTO_IF.
This is not ideal either but at least an order that should work for
the moment and can be re-fined with the VIMAGE merge, once this will
actually work with more than one network stack.
MFC after: 3 days
c9c086db96