updated.

INSERT ... ON DUPLICATE KEY UPDATE reports that a record was updated when
the duplicate key occurs even if the record wasn't actually changed
because the update values are the same as those in the record.

Now the compare_record() function is used to check whether the record was
changed and the update of a record reported only if the record differs
from the original one.


sql/sql_update.cc:
  Bug#19978: INSERT .. ON DUPLICATE erroneously reports some records were
  updated.
  The compare_record() function was changed to non-static one.
sql/sql_insert.cc:
  Bug#19978: INSERT .. ON DUPLICATE erroneously reports some records were
  updated.
  Now the compare_record() function is used to check whether the record was
  changed and the update of a record reported only if the record differs
  from the original one.
sql/mysql_priv.h:
  Bug#19978: INSERT .. ON DUPLICATE erroneously reports some records were
  updated.
  Added the prototype of the compare_record() function.
mysql-test/t/insert_select.test:
  Added a test case for bug#19978: INSERT .. ON DUPLICATE erroneously reports
  some records were updated.
mysql-test/r/insert_select.result:
  Added a test case for bug#19978: INSERT .. ON DUPLICATE erroneously reports
  some records were updated.