ver 5.0 and 5.1 refinement.
adding to the MAX_SIZE_LOG_EVENT_STATUS estimation status vars and 
EXECUTE_LOAD_QUERY_EXTRA_HEADER_LEN


sql/log_event.cc:
  assertion on size of status vars
sql/log_event.h:
  MAX_SIZE_LOG_EVENT_STATUS as the max bytes of contribution of status vars into repl
  message; MAX_SIZE_LOG_EVENT_STATUS is getting more wrt to 4.1 version.