a limitation of yesterday's implementation:
if there was an unfinished transaction (COMMIT not typed), and some MyISAM tables were
then updated, and then mysqld crashes, then at restart the server would use the too old
binlog offset known by InnoDB to cut the binlog, thus cutting the successful MyISAM
updates. We fix this by reporting the binlog offset into InnoDB even if InnoDB was not
affected at all by the update.
But the feature is still disabled until we decide if it can go into 4.1.3.


sql/handler.cc:
  How we report the binlog offset into InnoDB:
  - if the update affected InnoDB, it will happen naturally
  - otherwise (for example MyISAM update not in an InnoDB transaction), we explicitely report it.
sql/handler.h:
  removing warning (noticed this)
sql/log.cc:
  clearer messages when truncating binlog.
sql/mysql_priv.h:
  need to see opt_innodb_safe_binlog in handler.cc
sql/mysqld.cc:
  No innodb-safe-binlog if no InnoDB.
  Updating message as now we work with MyISAM.