Run goto_program.update() after adding instructions

remove_returnst::do_function_calls may introduce new instructions. Doing so
requires a call to goto_programt::update to ensure instruction numbers are
assigned.

Author: tautschnig

src/goto-programs/remove_returns.cpp

@@ -145,6 +145,8 @@ void remove_returnst::do_function_calls(
   function_is_stubt function_is_stub,
   goto_programt &goto_program)
 {
+  bool requires_update = false;
+
   Forall_goto_program_instructions(i_it, goto_program)
   {
     if(i_it->is_function_call())
@@ -221,10 +223,15 @@ void remove_returnst::do_function_calls(
             t_d->source_location=i_it->source_location;
             t_d->code = code_deadt(*return_value);
           }
+
+          requires_update = true;
         }
       }
     }
   }
+
+  if(requires_update)
+    goto_program.update();
 }
 
 void remove_returnst::operator()(goto_functionst &goto_functions)