- fix compile failure on QNX and FreeBSD


sql/event_executor.cc:
  time_t and my_time_t seem have the same length so cast
  in tztime.cc it's already done this way.
  Precautionary check at runtime about the sizes of my_time_t and time_t
sql/event_timed.cc:
  do time_t* cast to satisfy compilers on various platforms
  (QNX, FreeBSD)