Signed-off-by: zhoufeng <zhoufeng54@huawei.com>

Merge pull request !1359 from ZhangQinghua/master

1. Remove the records of user graphs;
2. Remove the records of user value nodes;
3. Remove the records of user cnodes;
4. Add the records of users, and the API to access the users of graph, value node, and cnode;
5. Fix issue:User cnode record may point to its own graph, when combine the user(caller) and used one(callee);
6. Fix issue:User graphs never update itself after its first creation.

Signed-off-by: leonwanghui <leon.wanghui@huawei.com>