HBASE-7845 optimize hfile index key

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460232 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8178 IPCUtil produces a LOT of WARN log spew; ADDENDUM

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.95@1460239 13f79535-47bb-0310-9956-ffa450edef68