Bug#12713 "Error in a stored function called from a SELECT doesn't

cause ROLLBACK of statement", part 1. Review fixes.

Do not send OK/EOF packets to the client until we reached the end of 
the current statement.
This is a consolidation, to keep the functionality that is shared by all 
SQL statements in one place in the server.
Currently this functionality includes:
- close_thread_tables()
- log_slow_statement().

After this patch and the subsequent patch for Bug#12713, it shall also include:
- ha_autocommit_or_rollback()
- net_end_statement()
- query_cache_end_of_result().

In future it may also include:
- mysql_reset_thd_for_next_command().

sql/repl_failsafe.cc

@@ -685,7 +685,7 @@ int connect_to_master(THD *thd, MYSQL* mysql, Master_info* mi)
 
   if (!mi->host || !*mi->host)			/* empty host */
   {
-    strmov(mysql->net.last_error, "Master is not configured");
+    strmov(mysql->net.client_last_error, "Master is not configured");
     DBUG_RETURN(1);
   }
   mysql_options(mysql, MYSQL_OPT_CONNECT_TIMEOUT, (char *) &slave_net_timeout);
@@ -880,6 +880,8 @@ bool load_master_data(THD* thd)
 	cleanup_mysql_results(db_res, cur_table_res - 1, table_res);
 	goto err;
       }
+      /* Clear the result of mysql_create_db(). */
+      thd->main_da.reset_diagnostics_area();
 
       if (mysql_select_db(&mysql, db) ||
 	  mysql_real_query(&mysql, STRING_WITH_LEN("SHOW TABLES")) ||