Squashed 'src/rocksdb/' content from commit 457bae6

git-subtree-dir: src/rocksdb
git-subtree-split: 457bae6911343c2e03222e24d0c946b94dca82b4
Merge commit '8514b88974c71c0fa85bb154507536ee49c33458' as 'src/rocksdb'
Changes to support unity build:
* Remove extra definition of TotalFileSize
* Remove extra definition of ClipToRange
* Move EncodedFileMetaData out from anonymous namespace
* Move version_set Saver to its own namespace
* Move some symbols into a named namespace
* Move symbols out of anonymous namespace (prevents warning)
* Make BloomHash inline
Update rocksdb unity build