Minor corrections to resolve -WShadow build problems with RocksJava code.
Summary: Add basic Java binding for rocksdb::Env. Test Plan: make rocksdbjava make jtest cd java ./jdb_bench.sh --max_background_compactions=1 ./jdb_bench.sh --max_background_compactions=10 Reviewers: sdong, ankgup87, haobo Reviewed By: haobo Subscribers: leveldb Differential Revision: https://reviews.facebook.net/D18903