too big by 6 bytes. So I add code to substract 6 bytes if the master is 3.23.
This is not perfect (because it won't work if the slave I/O thread has not
noticed yet that the master is 3.23), but as long as the slave I/O thread
starts Exec_master_log_pos will be ok.
It must be merged to 4.1 but not to 5.0 (or it can be, because of #if MYSQL_VERSION_ID),
because 5.0 already works if the master is 3.23 (and in a more natural way:
in 5.0 we store the end_log_pos in the binlog and relay log).
I had to move functions from slave.h to slave.cc to satisfy gcc.


sql/log_event.cc:
  make the event's length 6 bytes shorter if the master is 3.23
sql/slave.cc:
  Moving several st_relay_log_info methods out of the declaration of the struct,
  because gcc complained that 'mi' was not declared.
  Substracting 6 bytes from the event's length in inc_pos() if the master is 3.23.
sql/slave.h:
  moving several methods out of the declaration of st_relay_log_info.
  Removing 'inline', let's have the compiler decide.