Summary:
Current `log::Reader` does not perform retry after encountering `EOF`. In the future, we need the log reader to be able to retry tailing the log even after `EOF`.

Current implementation is simple. It does not provide more advanced retry policies. Will address this in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4394

Differential Revision: D9926508

Pulled By: riversand963

fbshipit-source-id: d86d145792a41bd64a72f642a2a08c7b7b5201e1