Manual merge from mysql-trunk-merge.

include/myisam.h

@@ -432,6 +432,10 @@ typedef struct st_mi_check_param
   const char *db_name, *table_name;
   const char *op_name;
   enum_mi_stats_method stats_method;
+#ifdef THREAD
+  pthread_mutex_t print_msg_mutex;
+  my_bool need_print_msg_lock;
+#endif
 } MI_CHECK;
 
 typedef struct st_sort_ft_buf