Fix Rocksdb lite build failure in forward_iterator_bench
Fix Rocksdb lite build failure in forward_iterator_bench

Summary:
Fixed Rocksdb lite build failure in forward_iterator_bench by
defining main for the ROCKSDB_LITE case

Test Plan: build ROCKSDB_LITE

Reviewers: anthony, yhchiang, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D50733

hobinyoon/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,Andymic/rocksdb,ryneli/rocksdb,Vaisman/rocksdb,wenduo/rocksdb,wenduo/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,jalexanderqed/rocksdb,facebook/rocksdb,hobinyoon/rocksdb,wat-ze-hex/rocksdb,flabby/rocksdb,flabby/rocksdb,norton/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,OverlordQ/rocksdb,bbiao/rocksdb,ryneli/rocksdb,SunguckLee/RocksDB,jalexanderqed/rocksdb,SunguckLee/RocksDB,ryneli/rocksdb,bbiao/rocksdb,bbiao/rocksdb,tsheasha/rocksdb,ryneli/rocksdb,Vaisman/rocksdb,vmx/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,facebook/rocksdb,wenduo/rocksdb,OverlordQ/rocksdb,bbiao/rocksdb,wenduo/rocksdb,wat-ze-hex/rocksdb,Vaisman/rocksdb,SunguckLee/RocksDB,ryneli/rocksdb,bbiao/rocksdb,tsheasha/rocksdb,hobinyoon/rocksdb,tsheasha/rocksdb,Vaisman/rocksdb,wenduo/rocksdb,ryneli/rocksdb,Andymic/rocksdb,jalexanderqed/rocksdb,jalexanderqed/rocksdb,flabby/rocksdb,flabby/rocksdb,wat-ze-hex/rocksdb,facebook/rocksdb,hobinyoon/rocksdb,norton/rocksdb,vmx/rocksdb,jalexanderqed/rocksdb,hobinyoon/rocksdb,facebook/rocksdb,Vaisman/rocksdb,wenduo/rocksdb,norton/rocksdb,norton/rocksdb,vmx/rocksdb,facebook/rocksdb,SunguckLee/RocksDB,flabby/rocksdb,OverlordQ/rocksdb,Vaisman/rocksdb,hobinyoon/rocksdb,vmx/rocksdb,hobinyoon/rocksdb,jalexanderqed/rocksdb,Andymic/rocksdb,bbiao/rocksdb,tsheasha/rocksdb,wenduo/rocksdb,norton/rocksdb,flabby/rocksdb,ryneli/rocksdb,wat-ze-hex/rocksdb,tsheasha/rocksdb,facebook/rocksdb,flabby/rocksdb,OverlordQ/rocksdb,norton/rocksdb,vmx/rocksdb,vmx/rocksdb,OverlordQ/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,hobinyoon/rocksdb,facebook/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,OverlordQ/rocksdb,bbiao/rocksdb,wenduo/rocksdb,norton/rocksdb,jalexanderqed/rocksdb,Andymic/rocksdb,tsheasha/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,norton/rocksdb,facebook/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,Vaisman/rocksdb,OverlordQ/rocksdb