Remove rocksdb in preparation for git-subtree add
Squashed 'src/rocksdb/' content from commit 37c6740

git-subtree-dir: src/rocksdb
git-subtree-split: 37c6740c383bb9a6ee2747b04f08bc77fcfa10c5
Merge commit '8e2460a3a22610cbbcffde99adddcb8aec9ff13b' as 'src/rocksdb'