compilation fix #1455

contracts/eosio.system/producers_election.hpp

@@ -104,11 +104,12 @@ namespace eosiosystem {
             time refund_time;
 
             uint64_t primary_key() const { return id; }
+            uint64_t rt() const { return refund_time; }
             EOSLIB_SERIALIZE( unstake_request, (id)(account)(amount)(refund_time) )
          };
 
          typedef eosio::multi_index< N(unstakerequests), unstake_request,
-                                     indexed_by<N(bytime), member<unstake_request, time, &unstake_request::refund_time> >
+                                     indexed_by<N(bytime), const_mem_fun<unstake_request, uint64_t, &unstake_request::rt> >
                                      > unstake_requests_table;
 
          struct unstake_requests_count {