all tables suggested by prelocking algorithm.
Added test for bug #11889 "Server crashes when dropping trigger using stored
routine" (which was fixed by previous patch).


mysql-test/r/trigger.result:
  Since we are using open_ltable() now to open table for trigger creation, code
  for error when we try to create trigger on view has changed to equivalent one.
  Added test for bug #11889 "Server crashes when dropping trigger using stored
  routine".
mysql-test/t/trigger.test:
  Since we are using open_ltable() now to open table for trigger creation, code
  for error when we try to create trigger on view has changed to equivalent one.
  Added test for bug #11889 "Server crashes when dropping trigger using stored
  routine".
sql/sql_trigger.cc:
  mysql_create_or_drop_trigger():
    It is better to open only table for which we are going to create or drop
    trigger with open_ltable() since we don't really need working prelocking
    in this case.