is executed, even if the transaction spans on >=2 relay logs (bug #53).
New variable relay_log_purge =0|1
New test to verify bug #53


sql/log.cc:
  Now we purge a relay log only when we are sure we won't need it,
  i.e. we have executed the final query (if autocommit=1) or the COMMIT.
sql/log_event.cc:
  Better tracking of the relay log's name and position
  lastly executed, even if we are in a transaction which spans on
  2 or more relay logs.
sql/mysql_priv.h:
  new option relay_log_purge (the user can now decide himself
  if he wants his relay logs to be automatically purged or not,
  we don't make unsafe guesses like before)
sql/mysqld.cc:
  new option --innodb (replaces --skip-innodb).
  Useful for the test suite : we have skip-innodb in mysql-test-run,
  but we can ('-opt.info' file) choose to start the server with
  InnoDB for this test only.
  New option --bdb
sql/repl_failsafe.cc:
  Better tracking of the relay log's name and position
  lastly executed, even if we are in a transaction which spans on
  2 or more relay logs.
sql/set_var.cc:
  new variable relay_log_purge
sql/slave.cc:
  Better tracking of the relay log's name and position
  lastly executed, even if we are in a transaction which spans on
  2 or more relay logs.
  Now we purge a relay log only when we are sure we won't need it,
  i.e. we have executed the final query (if autocommit=1) or the COMMIT
sql/slave.h:
  Better tracking of the relay log's name and position
  lastly executed, even if we are in a transaction which spans on
  2 or more relay logs.
sql/sql_class.h:
  prototypes change
sql/sql_parse.cc:
  removed thd argument (was not used in the function's body)
sql/sql_repl.cc:
  Better tracking of the relay log's name and position
  lastly executed, even if we are in a transaction which spans on
  2 or more relay logs.
  Turn relay_log_purge silently off when someone does CHANGE
  MASTER TO RELAY_LOG_*