Fails to build with Clang 11

[thekvs]

/<skipped>/rocksdb/options/options_helper.cc:659:19: error: loop variable 'iter' creates a copy from type 'const std::__1::pair<const std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, rocksdb::OptionTypeInfo>' [-Werror,-Wrange-loop-construct]
  for (const auto iter : type_info) {
                  ^
/<skipped>/rocksdb/options/options_helper.cc:659:8: note: use reference type 'const std::__1::pair<const std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, rocksdb::OptionTypeInfo> &' to prevent copying
  for (const auto iter : type_info) {
       ^~~~~~~~~~~~~~~~~
                  &

RocksDB version 6.11.4
Clang version 11
Ubuntu 18.04.5 LTS

[jay-zhuang]

It should already be fixed by #7025

Please re-open if needed.