Checks for temporary tables are only done if they have been created

Previously all queries were inspected for CREATE, DROP and SELECT statements
which targeted temporary tables even if they haven't been created.

server/modules/include/readwritesplit.h

@@ -294,6 +294,7 @@ struct router_client_session {
         bool             rses_transaction_active;
         bool             rses_load_active; /*< If LOAD DATA LOCAL INFILE is
                                             * being currently executed */
+        bool             have_tmp_tables;
         uint64_t         rses_load_data_sent; /*< How much data has been sent */
         DCB* client_dcb;
         int             pos_generator;