BUG #11754979 - 46675: ON DUPLICATE KEY UPDATE AND UPDATECOUNT() POSSIBLY WRONG 

The mysql_affected_rows() client call returns 3 instead of 2 on
INSERT ... ON DUPLICATE KEY UPDATE query with a duplicated key value.

The fix for the old bug #29692 was incomplete: unnecessary double
increment of "touched" rows still happened.

This bugfix removes:
1) unneeded increment of "touched" rows and
2) useless double resetting of auto-increment value.


sql/sql_insert.cc:
  write_record() function:
  Unneeded increment of "touched" rows and useless double resetting
  of auto-increment value has been removed.
tests/mysql_client_test.c:
  New test case.