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().

libmysqld/libmysqld.c

@@ -209,8 +209,9 @@ mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
   DBUG_RETURN(mysql);
 
 error:
-  DBUG_PRINT("error",("message: %u (%s)", mysql->net.last_errno,
-		      mysql->net.last_error));
+  DBUG_PRINT("error",("message: %u (%s)",
+                      mysql->net.client_last_errno,
+                      mysql->net.client_last_error));
   {
     /* Free alloced memory */
     my_bool free_me=mysql->free_me;