Problem: mysqlbinlog exits without any error code in case of
file write error. It is because of the fact that the calls
to Log_event::print() method does not return a value and the
thus any error were being ignored.

Resolution: We resolve this problem by checking for the 
IO_CACHE::error == -1 after every call to Log_event:: print()
and terminating the further execution.

client/mysqlbinlog.cc:
  - handled error conditions during event->print() calls
  - added check for error in end_io_cache()
mysys/my_write.c:
  Added debug code to simulate file write error.
  error returned will be ENOSPC=> error no space on the disk
sql/log_event.cc:
  Added debug code to simulate file write error, by reducing the size of io cache.