Summary:
Fix the bug where if blob db garbage collection revmoe keys with newer version. It shouldn't delete the key from base db when sequence number in base db is not equal to the one in blob log.
Closes https://github.com/facebook/rocksdb/pull/2678
Differential Revision: D5549752
Pulled By: yiwu-arbug
fbshipit-source-id: abb8649260963b5c389748023970fd746279d227
2c45ada4c4