[CS] Remove function component constraints

FunctionInput relies on being able to represent
parameter lists as tuples, which won't be possible
once parameter flags are stripped from tuple types.
FunctionResult is reasonable, but is currently
unused.

lib/Sema/CSBindings.cpp

@@ -1336,8 +1336,6 @@ void PotentialBindings::infer(Constraint *constraint) {
   case ConstraintKind::EscapableFunctionOf:
   case ConstraintKind::OpenedExistentialOf:
   case ConstraintKind::KeyPath:
-  case ConstraintKind::FunctionInput:
-  case ConstraintKind::FunctionResult:
   case ConstraintKind::ClosureBodyElement:
   case ConstraintKind::Conjunction:
     // Constraints from which we can't do anything.