Summary:
This is the initial PR to support adding fuzz tests to RocksDB.
It includes the necessary build infrastructure, and includes an example fuzzer.
There is also a README serving as the tutorial for how to add more tests.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7685
Test Plan: Manually build and run the fuzz test according to README.
Reviewed By: pdillinger
Differential Revision: D25013847
Pulled By: cheng-chang
fbshipit-source-id: c91e3b337398d7f4d8f769fd5091cd080487b171
