HBASE-11460 Deadlock in HMaster on masterAndZKLock in HConnectionManager
Revert "HBASE-11492 The servers do not honor the tcpNoDelay option"

This reverts commit 79676f15f4c63504d60ca9b7046cb7346e9c3df6.
HBASE-11487 ScanResponse carries non-zero cellblock for CloseScanRequest (Shengzhe Yao)