mvcc/backend: code format optimization
mvcc/backend: code format optimization

gyuho/etcd,mqliang/etcd,li-ang/etcd,joshix/etcd,ajityagaty/etcd,cockroachdb/etcd,xiang90/etcd,etcd-io/etcd,mkumatag/etcd,rnaveiras/etcd,cockroachdb/etcd,gyuho/etcd,xiang90/etcd,mqliang/etcd,ajityagaty/etcd,etcd-io/etcd,dannysauer/etcd,dannysauer/etcd,rnaveiras/etcd,mqliang/etcd,coreos/etcd,li-ang/etcd,mkumatag/etcd,coreos/etcd,mkumatag/etcd,rnaveiras/etcd,joshix/etcd,ajityagaty/etcd,etcd-io/etcd