Summary:
In `Table::BlockReader()` when there was no block cache `didIO` was not set.
This didn't seem to matter as `didIO` is only used to trigger seek compactions. However, I would like it if someone else could check that is the case.
Test Plan: `make check OPT="-g -O3"`
Reviewers: dhruba, vamsi
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D8133