Added support for a LOCK TABLES...WHERE ENGINE = InnoDB query which sets

transactional table locks to tables mentioned in the query. These locks
are released at the end of the transaction automatically.
This is fix for bugs #5655, #5998 and issue #3762.

sql/sql_lex.h

@@ -87,6 +87,7 @@ enum enum_sql_command {
   SQLCOM_PREPARE, SQLCOM_EXECUTE, SQLCOM_DEALLOCATE_PREPARE,
   SQLCOM_CREATE_VIEW, SQLCOM_DROP_VIEW,
   SQLCOM_CREATE_TRIGGER, SQLCOM_DROP_TRIGGER,
+  SQLCOM_LOCK_TABLES_TRANSACTIONAL,
   /* This should be the last !!! */
   SQLCOM_END
 };