add_wrapped_bloom_test

Summary:
1. wrap a filter policy like what fbcode/multifeed/rocksdb/MultifeedRocksDbKey.h
   to ensure that rocksdb works fine after filterpolicy interface change

Test Plan: 1. valgrind ./bloom_test

Reviewers: ljin, igor, yhchiang, dhruba, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23229