We don't want the update to abort when IGNORE is specified


mysql-test/r/update.result:
  Bug#5553 - UPDATE IGNORE fails on dup key
    New test
mysql-test/t/update.test:
  Bug#5553 - UPDATE IGNORE fails on dup key
    New test
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted