fix #7499 - add another way to avoid adding user-defined functions to…

… models if user don't want it

- you can already do model.user_functions=false
- now you can also specify smtlib2_compliant (globally) and get smtlib2 behavior

src/smt/smt_context.cpp

@@ -4787,7 +4787,9 @@ namespace smt {
 
     void context::add_rec_funs_to_model() {
         model_params p;
-        if (m_model && p.user_functions())
+        auto smtlib2_compliant = gparams::get_value("smtlib2_compliant");
+
+        if (m_model && p.user_functions() && smtlib2_compliant != "true")
             m_model->add_rec_funs();
     }