RocksDB does not build on macOS

[ 11%] Building CXX object storage/rocksdb/CMakeFiles/rocksdblib.dir/rocksdb/db/auto_roll_logger.cc.o

In file included from /Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/tools/ldb_tool.cc:7:

In file included from /Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/include/rocksdb/ldb_tool.h:9:

/Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/include/rocksdb/db.h:17:10: fatal error: 'unordered_map' file not found

#include <unordered_map>

         ^

[ 11%] Building C object strings/CMakeFiles/strings.dir/strmov_overlapp.c.o

In file included from /Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/db/auto_roll_logger.cc:6:

In file included from /Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/db/auto_roll_logger.h:13:

/Users/buildbot/maria-slave/mac-1012-bintar/build/storage/rocksdb/rocksdb/db/filename.h:14:10: fatal error: 'unordered_map' file not found

#include <unordered_map>

         ^

[ 11%] Building C object strings/CMakeFiles/strings.dir/my_strchr.c.o

1 error generated.

make[2]: *** [storage/rocksdb/CMakeFiles/rocksdb_tools.dir/rocksdb/tools/ldb_tool.cc.o] Error 1

make[1]: *** [storage/rocksdb/CMakeFiles/rocksdb_tools.dir/all] Error 2

make[1]: *** Waiting for unfinished jobs....

[ 11%] Building C object storage/mroonga/vendor/groonga/lib/CMakeFiles/libgroonga.dir/ctx_impl_mrb.c.o

1 error generated.

make[2]: *** [storage/rocksdb/CMakeFiles/rocksdblib.dir/rocksdb/db/auto_roll_logger.cc.o] Error 1

make[1]: *** [storage/rocksdb/CMakeFiles/rocksdblib.dir/all] Error 2