message: Remove pre-bios unused native currency code
diff: namespace eosio { namespace chain { namespace contracts {
  -void intialize_eosio_tokens(chainbase::database& db, const account_name& system_account, share_type initial_tokens) {
  - const auto& t_id = db.create<contracts::table_id_object>([&](contracts::table_id_object &t_id){
  - t_id.scope = system_account;
  - t_id.code = config::system_account_name;
  - t_id.table = N(currency);
  - });
  -
  - db.create<key_value_object>([&](key_value_object &o){
  - o.t_id = t_id.id;
  - o.primary_key = N(account);
  - o.value.insert(0, reinterpret_cast<const char *>(&initial_tokens), sizeof(share_type));
  - });
  -}
  -
  -static void modify_eosio_balance( apply_context& context, const account_name& account, share_type amt) {
  - const auto& t_id = context.find_or_create_table(config::system_account_name, account, N(currency));
  - uint64_t key = N(account);
  - share_type balance = 0;
  - context.front_record<key_value_index, by_scope_primary>(t_id, &key, (char *)&balance, sizeof(balance));
  -
  - balance += amt;
  -
  - context.store_record<key_value_object>(t_id, config::system_account_name, &key, (const char *)&balance, sizeof(balance));
  -}
  -
  -
  void validate_authority_precondition( const apply_context& context, const authority& auth ) {
  for(const auto& a : auth.accounts) {
  context.db.get<account_object, by_name>(a.permission.actor);
  