touched but not actually changed.

The LAST_INSERT_ID() is reset to 0 if no rows were inserted or changed.
This is the case when an INSERT ... ON DUPLICATE KEY UPDATE updates a row
with the same values as the row contains.

Now the LAST_INSERT_ID() values is reset to 0 only if there were no rows
successfully inserted or touched.
The new 'touched' field is added to the COPY_INFO structure. It holds the
number of rows that were touched no matter whether they were actually
changed or not.


sql/sql_class.h:
  Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
  
  The new 'touched' field is added to the COPY_INFO structure. It holds the
  number of rows that were touched no matter whether they were actually
  changed or not.
mysql-test/r/insert_update.result:
  Added a test case for the bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
mysql-test/t/insert_update.test:
  Added a test case for the bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
sql/sql_insert.cc:
  Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
  
  Now the LAST_INSERT_ID() values is reset to 0 only if there were no rows
  successfully inserted or touched.