Make ai_baset::operator() work with abstract_goto_modelt

There is no need to restrict it to goto_modelt, this makes it easier to use in
some contexts.

Author: hannes-steffenhagen-diffblue

src/analyses/ai.h

@@ -68,12 +68,12 @@ class ai_baset
   }
 
   /// Run abstract interpretation on a whole program
-  void operator()(const goto_modelt &goto_model)
+  void operator()(const abstract_goto_modelt &goto_model)
   {
-    const namespacet ns(goto_model.symbol_table);
-    initialize(goto_model.goto_functions);
-    entry_state(goto_model.goto_functions);
-    fixedpoint(goto_model.goto_functions, ns);
+    const namespacet ns(goto_model.get_symbol_table());
+    initialize(goto_model.get_goto_functions());
+    entry_state(goto_model.get_goto_functions());
+    fixedpoint(goto_model.get_goto_functions(), ns);
     finalize();
   }