Fixed a compile error in ROCKSDB_LITE

Summary: Fixed a compile error in ROCKSDB_LITE

Test Plan: make db_stress OPT=-DROCKSDB_LITE -j32

Reviewers: sdong, igor, anthony

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39201

include/rocksdb/immutable_options.h

@@ -95,11 +95,9 @@ struct ImmutableCFOptions {
 
   bool optimize_filters_for_hits;
 
-#ifndef ROCKSDB_LITE
   // A vector of EventListeners which call-back functions will be called
   // when specific RocksDB event happens.
   std::vector<std::shared_ptr<EventListener>> listeners;
-#endif  // ROCKSDB_LITE
 };
 
 }  // namespace rocksdb