We should not allow FLUSH statement to be executed inside both triggers
and stored functions.


mysql-test/r/sp-error.result:
  Updated test after replacing error, which is thrown when one uses FLUSH
  statement inside of stored function, with more specific.
  Also now we issue more general error when we barking about USE command
  in stored routines.
mysql-test/r/trigger.result:
  Added test for bug #12280 "Triggers: crash if flush tables"
mysql-test/t/sp-error.test:
  Updated test after replacing error, which is thrown when one uses FLUSH
  statement inside of stored function, with more specific.
  Also now we issue more general error when we barking about USE command
  in stored routines.
mysql-test/t/trigger.test:
  Added test for bug #12280 "Triggers: crash if flush tables"
sql/share/errmsg.txt:
  Removed ER_SP_NO_USE error. Now we use more general ER_SP_BADSTATEMENT in this
  case. Instead added error message for barking about statements which should not
  be allowed inside of stored functions or triggers.
  It is safe to do this since it is highly unprobable that someone will upgrade
  first to the new 5.0 release and then downgrade back to the old one.
sql/sql_parse.cc:
  reload_acl_and_cache():
    FLUSH TABLES and FLUSH PRIVILEGES should not be allowed if we are inside
    of stored function or trigger.
sql/sql_yacc.yy:
  We should not allow FLUSH statement inside both triggers and stored
  functions. Replaced error which is thrown in this case with more
  specific.
  Also now we issue more general ER_SP_BADSTATEMENT error when one tries
  to use USE command inside of stored routine.