From: @zh_qh
Reviewed-by: 
Signed-off-by:

Move auto monad eliminator out from CSE.
Eliminate auto monad nodes for output node.

The basic idea is: exploits data dependency to control the execution order
of side-effect operations, and keep the semantics of ANF unchanged.

The ControlDepend primitive is removed and there are two primitives added:

1. UpdateState:
```
  a = Assign(para, value)
```
became:
```
  a = Assign(para, value, u)
  u = UpdateState(u, a)
```

2. Load:
```
  x = Add(para, value)
```
became:
```
  p = Load(para, u)
  x = Add(p, value)
  u = UpdateState(u, p)
```

Merge pull request !4883 from zhoufeng/xiu-ba-ge

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

replace frontend/operator/ops.h in backend with base/core_ops.h as
backend should not use any frontend-only primitive

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

Merge pull request !3289 from ZhangQinghua/master