Summary:
Revert "Use function objects as deleters in the block cache (https://github.com/facebook/rocksdb/issues/6545)"
This reverts commit 6301dbe7a71d3663b87f66b3201ff8745bc48742.
Revert "Call out the cache deleter related interface change in HISTORY.md (https://github.com/facebook/rocksdb/issues/6606)"
This reverts commit 3a35542f8639cc9721db9fd71e964001f7291505.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6620
Test Plan: `make check`
Reviewed By: zhichao-cao
Differential Revision: D20773311
Pulled By: ltamasi
fbshipit-source-id: 7637a761f718f323ef0e7da959462e8fb06e7a2b