message: Added virtual destructor to base class PetscPreconditionerFactory
diff: @@ -376,8 +376,9 @@ private:
  class PetscPreconditionerFactory
  {
  public:
  - PetscPreconditionerFactory() {};
  - virtual Solver *NewPreconditioner(OperatorHandle& oph) = 0;
  + PetscPreconditionerFactory() {}
  + virtual Solver *NewPreconditioner(const OperatorHandle& oh) = 0;
  + virtual ~PetscPreconditionerFactory() {}
  };
  // Forward declarations of helper classes
  