Summary:
Forward compatibility with new defaults only starts from 5.16
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6598

Test Plan: facebook automated test (so much easier than running myself)

Reviewed By: riversand963

Differential Revision: D20665553

Pulled By: pdillinger

fbshipit-source-id: b846bfaccf4d0946f92d323a3b4ee6e3e548df93