don't `git submodule update` from rocksdb/CMakeLists.txt (#492)
don't `git submodule update` from rocksdb/CMakeLists.txt (#492)

we now have cmake/submodules.cmake that updates all submodules

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2