HBASE-9949 Fix the race condition between Compaction and StoreScanner.init



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.96@1542518 13f79535-47bb-0310-9956-ffa450edef68
HBASE-9949 Addendum removes readpoint parameter for getScanner()



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.96@1542528 13f79535-47bb-0310-9956-ffa450edef68