Block internal_stats in ROCKSDB_LITE

Summary: Block internal_stats in ROCKSDB_LITE.

Test Plan: make OPT=-DROCKSDB_LITE shared_lib

Reviewers: ljin, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D29541
[RocksJava] Sigsegv fix for MergerOperatorByName
[RocksJava] Incoroporated changes for D29013