Fixed didIO not being set with no block_cache
Fixed didIO not being set with no block_cache

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

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ottdorf/rocksdb,wat-ze-hex/rocksdb,dkorolev/rocksdb,temicai/rocksdb,flabby/rocksdb,wenduo/rocksdb,JackLian/rocksdb,wlqGit/rocksdb,wskplho/rocksdb,kaschaeffer/rocksdb,JoeWoo/rocksdb,bbiao/rocksdb,luckywhu/rocksdb,JoeWoo/rocksdb,amyvmiwei/rocksdb,virtdb/rocksdb,IMCG/RcoksDB,hobinyoon/rocksdb,anagav/rocksdb,temicai/rocksdb,OverlordQ/rocksdb,NickCis/rocksdb,jalexanderqed/rocksdb,norton/rocksdb,virtdb/rocksdb,dkorolev/rocksdb,ylong/rocksdb,tschottdorf/rocksdb,msb-at-yahoo/rocksdb,JoeWoo/rocksdb,Andymic/rocksdb,wskplho/rocksdb,wlqGit/rocksdb,Applied-Duality/rocksdb,SunguckLee/RocksDB,tizzybec/rocksdb,sorphi/rocksdb,virtdb/rocksdb,wskplho/rocksdb,fengshao0907/rocksdb,makelivedotnet/rocksdb,JohnPJenkins/rocksdb,tizzybec/rocksdb,amyvmiwei/rocksdb,SunguckLee/RocksDB,JohnPJenkins/rocksdb,Applied-Duality/rocksdb,bbiao/rocksdb,IMCG/RcoksDB,rDSN-Projects/rocksdb.replicated,fengshao0907/rocksdb,amyvmiwei/rocksdb,ylong/rocksdb,tschottdorf/rocksdb,skunkwerks/rocksdb,amyvmiwei/rocksdb,JackLian/rocksdb,sorphi/rocksdb,vmx/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,tsheasha/rocksdb,wskplho/rocksdb,msb-at-yahoo/rocksdb,tizzybec/rocksdb,dkorolev/rocksdb,wenduo/rocksdb,vmx/rocksdb,norton/rocksdb,caijieming-baidu/rocksdb,jalexanderqed/rocksdb,wat-ze-hex/rocksdb,JohnPJenkins/rocksdb,RyanTech/rocksdb,anagav/rocksdb