Summary:
This is the second split of this pull request: https://github.com/facebook/rocksdb/pull/1891 which includes only the builder part. The testing will be included in the third split, where the reader is also included.
Closes https://github.com/facebook/rocksdb/pull/1952
Differential Revision: D4660272
Pulled By: maysamyabandeh
fbshipit-source-id: 36b3cf0