Add workaround for issue described in #6168.

This fixes the infinite unwinding by adding calls to `do_indirect_call_and_rtti_removal()`
before the contracts code invocation in `goto-instrument/`.

Author: NlightNFotis

src/goto-instrument/contracts/contracts.cpp

@@ -1268,5 +1268,8 @@ bool code_contractst::enforce_contracts(const std::set<std::string> &functions)
     if(!fail)
       fail = enforce_contract(function);
   }
+
+  apply_loop_contracts();
+
   return fail;
 }

src/goto-instrument/goto_instrument_parse_options.cpp

@@ -1154,6 +1154,7 @@ void goto_instrument_parse_optionst::instrument_goto_program()
     cmdline.isset(FLAG_ENFORCE_CONTRACT) ||
     cmdline.isset(FLAG_ENFORCE_ALL_CONTRACTS))
   {
+    do_indirect_call_and_rtti_removal();
     code_contractst cont(goto_model, log);
 
     if(cmdline.isset(FLAG_REPLACE_CALL))