stack's wait cost a lot of cpu time, use cuda kernel to do memory copy
will reduce cpu time.
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* modify fc to linear in sample code, test=develop

* remove FC, test=develop

* remove warnings, test=develop

* drop fluid/imperative/README.md , test=develop

* change fc to linear, test=develop

* polish code style, test=develop

Add coverage data processing tools.

1. Add a new input named batch_roi_nums for prroi_pool_op. batch_roi_nums includes the number of roi for each image in batch when rois is Tensor. This information is saved in rois's lod when rois is LoDTensor.
2. add grad check to prroi_pool_op and solve unnormal X grad diff in CPU.

* fix sample code, test=develop

* polish code style, test=develop

test=develop

* add TRT support for instance_norm op

windows conv_fusion failed as no kernel， explicit declare lambda
Signed-off-by: Nzhaoyuchen <zhaoyuchen01@baidu.com>

* add special way to add distribute vars， Update Pyramid hash op

* add erf op and python interface.

* add fp16 support for erf op.

* add unitests for erf op and its python interface.

* support elu activation double grad,test=develop

* delete the code commit in .cc,test=develop

* fix relu test unpass, test=develop

* add elu double grad kernel and unit test

* add caculate dX in elu double grad functor, test=develop

* update the commit code,test=develop

* add gelu plugin

* align trt bert with gpu

* add support for fused fc with relu,

* add unittest for bert trt

* add distributed_strategy

* register int/int64_t/float16 in  pow/square kernel,test=develop

* add abs/square/exp type,test=develop

* fix test_conv2d_ngraph for grad diff, test=develop

* register NoNeedBufferVarsInference for max_pool_grad_op, test=develop

* refine error message, test=develop

* fix numpy, test=develop

* disable test conv2d_ngraph_op, test=develop
Co-authored-by: NZhang Ting <709968123@qq.com>

* Add the dynamic load of nvrtc, and support runtime compiling of CUDA kernel using nvrtc.
test=develop

* Call CUDA driver api to launch the kernel compiled by nvrtc.
test=develop

* Disable for mac and windows.
test=develop

* Refine the codes to support manually specified num_threads and workload_per_thread.
test=develop

* Refine the CUDA kernel to support large dims.
test=develop

* Add DeviceCodePool to manage all device codes.

* Add the first implementation fusion_group op.

* Add unit-test for fusion_group op.

* Add the check of result.

* Add the check of nvrtc in unit-test.
test=develop

* Add comment to explain the inputs, outputs and features of fusion_group op.
test=develop

* Disable fusion_group op for mac and windows.
test=develop

* Make the compiling of device code return status instead of hanging up.
test=develop

* Add the check of whether there is CUDA driver library, and do not core dump when failing to call the CUDA driver API.

* Unify fusion_group_op's input and output names.
test=develop

* Add the check of CUDA driver library in unittest.
test=develop

* Refine the calling of PADDLE_ENFORCE.
test=develop

* test=develop fix generate_proposal_labesl op

* update error information about batch_norm_grad

* update bn,test=develop

* fix integer overflow in match_matrix test=develop

* fix integer overflow in match_matrix test=develop

* fix typo test=develop