HBASE-8547. Fix java.lang.RuntimeException: Cached an already cached block (Addendum2 to check cached buffers for equality)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1483476 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8505 References to split daughters should not be deleted separately from parent META entry

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1483481 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd