Fixes IncrClosureInference.changeFunctionalInterfaceParam test.
Temporary rules built as macro applications weren't computing hash
due to origin!=null condition. Also macro inputs weren't processed.
Stable hash for TypeVarSubstitution is defined because it's used in macro args.
In general, any classes used as constraint/predicate/macro args
must adhere to stable hashCode() contract: hash should change
if there're important changes that may influence typechecking result.
Otherwise there may be unnecessary incremental recomputations.
Relevant for MPSCR-62
f9ca9f2766