HBASE-20928 Rewrite calculation of midpoint - addendum (Xu Cang) Signed-off-by: tedyu <yuzhihong@gmail.com> Conflicts: hbase-common/src/main/java/org/apache/hadoop/hbase/io/encoding/RowIndexSeekerV1.java hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java Amending-Author: Andrew Purtell <apurtell@apache.org>