[CS] Don't record a generated and retired constraint

Retired constraints get added back to the inactive
list when a scope rolls back, and generated
constraints then get removed. So adding a
constraint as both is unnecessary.

Also assert that `addNewFailingConstraint` doesn't
get called with an active constraint.

Author: hamishknight

lib/Sema/CSSimplify.cpp

@@ -10080,22 +10080,13 @@ void ConstraintSystem::simplifyDisjunctionChoice(Constraint *choice) {
   case ConstraintSystem::SolutionKind::Error:
     if (!failedConstraint)
       failedConstraint = choice;
-    if (solverState)
-      solverState->retireConstraint(choice);
     break;
 
   case ConstraintSystem::SolutionKind::Solved:
-    if (solverState)
-      solverState->retireConstraint(choice);
     break;
 
   case ConstraintSystem::SolutionKind::Unsolved:
-    InactiveConstraints.push_back(choice);
-    CG.addConstraint(choice);
+    addUnsolvedConstraint(choice);
     break;
   }
-
-  // Record this as a generated constraint.
-  if (solverState)
-    solverState->addGeneratedConstraint(choice);
 }

lib/Sema/ConstraintSystem.h

@@ -2932,14 +2932,8 @@ class ConstraintSystem {
   /// Add a new constraint that we know fails.
   void addNewFailingConstraint(Constraint *constraint) {
     assert(shouldAddNewFailingConstraint());
+    assert(!constraint->isActive());
     failedConstraint = constraint;
-    failedConstraint->setActive(false);
-
-    // Record this as a newly-generated constraint.
-    if (solverState) {
-      solverState->addGeneratedConstraint(constraint);
-      solverState->retireConstraint(constraint);
-    }
   }
 
   /// Add a newly-generated constraint that is known not to be solvable