Summary:
When changing db iterator direction, we may perform a reseek.
Therefore, we should bump the NUMBER_OF_RESEEKS_IN_ITERATION counter.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8015

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D26755415

Pulled By: riversand963

fbshipit-source-id: 211f51f1a454bcda768fc46c0dce51edeb7f05fe