Remove now-unused solver_factoryt::solvert methods

With the preceding commit we now apply RAII, making default-constructing
unnecessary.

Author: tautschnig

src/goto-checker/solver_factory.cpp

@@ -87,12 +87,6 @@ solver_factoryt::solvert::stack_decision_procedure() const
   return *solver;
 }
 
-propt &solver_factoryt::solvert::prop() const
-{
-  PRECONDITION(prop_ptr != nullptr);
-  return *prop_ptr;
-}
-
 void solver_factoryt::set_decision_procedure_time_limit(
   decision_proceduret &decision_procedure)
 {

src/goto-checker/solver_factory.h

@@ -38,7 +38,6 @@ class solver_factoryt final
   class solvert final
   {
   public:
-    solvert() = default;
     explicit solvert(std::unique_ptr<decision_proceduret> p);
     solvert(std::unique_ptr<decision_proceduret> p1, std::unique_ptr<propt> p2);
     solvert(
@@ -47,7 +46,6 @@ class solver_factoryt final
 
     decision_proceduret &decision_procedure() const;
     stack_decision_proceduret &stack_decision_procedure() const;
-    propt &prop() const;
 
     void set_decision_procedure(std::unique_ptr<decision_proceduret> p);
     void set_prop(std::unique_ptr<propt> p);