Add the $anyinit cell and the formalff pass

These can be used to protect undefined flip-flop initialization values
from optimizations that are not sound for formal verification and can
help mapping all solver-provided values in witness traces for flows that
use different backends simultaneously.

passes/hierarchy/submod.cc

@@ -260,6 +260,7 @@ struct SubmodWorker
 		}
 
 		ct.setup_internals();
+		ct.setup_internals_anyinit();
 		ct.setup_internals_mem();
 		ct.setup_stdcells();
 		ct.setup_stdcells_mem();