Introduced EVENTS.EVENT_DEFINITION, like ROUTINES.ROUTINE_DEFINITION
Hence, the contents of the current EVENTS.EVENT_BODY become the contents
of EVENT_DEFINITION. EVENT_BODY will contain always, for now, "SQL" (wo
quotes).


mysql-test/r/events.result:
  update result
  event_body -> event_definition
  event_body -> SQL
mysql-test/r/events_grant.result:
  update result
  event_body -> event_definition
  event_body -> SQL
mysql-test/r/information_schema.result:
  update result
  event_body -> event_definition
mysql-test/t/events.test:
  update result
  event_body -> event_definition
  event_body -> SQL
mysql-test/t/events_grant.test:
  update result
  event_body -> event_definition
  event_body -> SQL
sql/sql_show.cc:
  Introduce enum_i_s_events_fields, because I hate recounting
  all the time a field is changed.
  Rename EVENT_BODY to EVENT_DEFINITION
  Introduce EVENT_BODY after that to be "SQL"
  (final fix for bug#16992 Events: Information schema troubles ) ?