ensure limit children are safe for race conditions

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/solver/solver.h

@@ -41,7 +41,6 @@ public:
      - parameter setting (updt_params)
      - statistics
      - results based on check_sat_result API
-     - interruption (set_cancel)
 */
 class solver : public check_sat_result {
 public:
@@ -105,14 +104,6 @@ public:
     */
     virtual lbool check_sat(unsigned num_assumptions, expr * const * assumptions) = 0;
 
-    /**
-       \brief Interrupt this solver.
-    */
-    //void cancel() { set_cancel(true); }
-    /**
-       \brief Reset the interruption.
-    */
-    //void reset_cancel() { set_cancel(false); }
 
     /**
        \brief Set a progress callback procedure that is invoked by this solver during check_sat.
@@ -156,9 +147,6 @@ public:
         ~scoped_push() { if (!m_nopop) s.pop(1); }
         void disable_pop() { m_nopop = true; }
     };
-
-protected:
-    //virtual void set_cancel(bool f) = 0;
 };
 
 #endif