Adapt to upstream change in write_goto_binary interface and languaget

* write_goto_binary now takes a goto_modelt
* languaget now uses the override keyword

Author: smowton

src/jsil/jsil_language.h

@@ -55,7 +55,7 @@ class jsil_languaget:public languaget
     const namespacet &ns) override;
 
   std::unique_ptr<pretty_printert>
-    get_pretty_printer(const namespacet &);
+    get_pretty_printer(const namespacet &) override;
 
   virtual bool to_expr(
     const std::string &code,