fix build for raspberry 2
fix build for raspberry 2

fix #810

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