BUG#2826 "Seconds behind master weirdness"
(sometimes this column of SHOW SLAVE STATUS shows a very big value,
in fact a small negative number casted to ulonglong).
This problem was reported by only one user, but which uses
synchronized time between his servers.
As suggested by the user, to hide this I display max(0, the value)
so that it will be less confusing. For a user, seeing 0 is probably
better than seeing -1 (both tell you that the slave is very close
to the master).


sql/slave.cc:
  Don't display a negative Seconds_Behind_Master in SHOW SLAVE STATUS.