Submitting patch on Guilhem's behalf (he found the solution).
  
Correcting a typo that caused very big increases in memory usage when
more memory needed to be allocated for row-based events. Also correcting
a border case check when more memory needed to be allocated.


sql/log_event.cc:
  Correcting typo that caused very big increases in memory allocation.
  Correcting border case for when more memory should be allocated.