* code clean - refine ARM

cmake enhancement:

- add lite_cc_library and lite_cc_test

code clean:

- remove ARM feed and fetch kernels, reuse the Host's

remove unnecessary comments

* add cmake

* update

* fix proto pd

* fix compile

* tmp save

* fix protobuf device version

* fix protobuf and host compile

* fix std c++11 support on android

* change array to vector to fix ndk c++_static

* fix rt and add dockerfile

* fix android compile issue with latest merge

* init arm kernels

* enable run on arm

* update format

* update format

* update format

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make typesystem simpler

* reset drop local scope counter
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refine code

fuse cublas  calling and kernels into one cuda kernel.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* Add conv2d_grad_grad_op
* Extracte the cuDNN conv algo searching code in conv_cudnn_helper.h.
    - Now use it in conv2d_grad_grad.
    - Will simply the searching code in conv2d and conv2d_grad in next PR.
* Enhance and fix bug in unit testing of gradient_checker.
* Support to fetch empty variables，return None in Python.

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1. infernce multi card occupy
2. facebox model inference occupy too much
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* test=develop
add elementwise_mod and elementwise_floordiv, fix equation problem in elementwise_mod

* fix train_from_dataset and infer_from_dataset example

* add inductive dim for data_reader, example: shape=[-1, 1], then -1 will be inducted through run-time reading of number of elements

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* Fix API example code of save_inference_model

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* Add "import" in exmaple of save_inference_model

* Fix typo "exsample" -> "example"

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* modified formula for lrn

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* modified api.spec

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* Refine elementwise kernel.

Add a simple cuda kernel if grad x and y both exist
Use 2D block cuda kernel to do broadcast.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine code.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* refine code.

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Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

Fix the following API examples:

paddle.fluid.scope_guard
paddle.fluid.backward.append_backward
paddle.fluid.cpu_places
paddle.fluid.cuda_pinned_places
paddle.fluid.cuda_places
paddle.fluid.in_dygraph_mode
paddle.fluid.CUDAPlace
paddle.fluid.CPUPlace
paddle.fluid.CUDAPinnedPlace

* Optimize the cuda implementation of sum_op, which add two lod_tensors inplace.
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* Use eigen to add to tensors.
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* fix shape_check; test=develop

* fix format; test=develop

* fix format; test=develop

* fix ddim bug; test=develop

* fix c++ format; test=develop

* change function name; test=develop

* fix API examples, test=develop

* added lrn op test=develop

* Added CreateConstant method test=develop

* avoid duplicates test=develop

added printing data type to differentiate int8 and fp32 latency results

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* polish doc
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* updata parallel executor doc
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* update API.spec
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* polish code
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