Parsing of CREATE/ALTER EVENT statement was crashing because of early
initialization done during parsing, instead in the after parsing phase.
Moreover, we don't want SUBqueries in CREATE/ALTER EVENT therefore we
disable them, though it is possible to make them work. It can be emulated
inside SP with a cursor and SP variable (CREATE/ALTER EVENT can still
accept variables as values).


mysql-test/r/events_bugs.result:
  update result
mysql-test/t/events_bugs.test:
  tests for bug#16384
sql/sql_yacc.yy:
  disallow subqueries when SQLCOM_CREATE_EVENT | SQLCOM_ALTER_EVENT
  The fix is not big, though lex->forbid_subqueries could have been introduced.
  Easier is just to set the sql_command and check in both rules where
  subqueries enter.