These ops are useful in control flow.

ocr_recognition fails, so add a path to handle small frame_size.

test=develop

* test=develop,fix rpc not wait in geo

* Add c++ global current tracer for dygraph, test=develop

* add tracer property in c++, test=develop

* support different place, test=develop

* add unittest for tracer, test=develop

* remove duplicate code and duplicate config of master+patch
* drop all ins which has conflict slot or size < merge_size
* user only need to set merge size，if ins num of same id is not equal to merge size, just drop these ins
* user must make sure master data and patch data has no same slot whose feasigns are both non-zero, otherwise these ins will be dropped. (slot list should still be the same of both master and patch)
* test=develop

test=develop

* support no need buffer vars in dygraph, test=develop

* fix inference compilation error, test=develop

* update no_need_buffer_vars_inference, test=develop

* add unittests for no_need_buffer_vars_context, test=develop

* refine no_need_buffer_vars by return ref, test=develop

* polish some codes, test=develop

fix squared_mat_sub_fuse_pass when elementwise_op input is from persistable param test=develop (#20960)

fix squared_mat_sub_fuse_pass when elementwise_op input is from persistable param

fix the bug of conv_transpose cudnn kernel: before version 1.6, the data_format is AnyLayout in inference model. When use version 1.6 and load the model which is saved by previous version, the error occurs.  This is because the cudnn kernel in version 1.6 is not compitable with Anylayout setting.

* don't expose numerous Tensor.set(), test=develop

* fix condition, test=develop

* fix float16 bug, test=develop

* feed should be Tensor or np.array, not Variable or number, test=develop

* use forcecast to copy numpy slice to new array, test=develop

* remove float16-uint16 hacking, test=develop

seems shuffle_sync cannot handle small size

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

* update pserver decay blocks

* update distributed notify handler

* fix PaddleCloud Role maker & add warning in distribute transpiler  & change rpc_retry_times

* maxout support channel_last input, test=develop

* modified details of Input(X) and Attr(groups, axis) in doc, test=develop

* refactor dygraph,test=develop

* fix failed unittest,test=develop

* polish code,test=develop

* check windows ci error,test=develop
try to fix windows ci error by np.allclose,test=develop

* polish vlog and profiler, test=develop

* try to fix preceding ops order,test=develop

* test transformer in windows ci, test=develop

* use python c-api to speed up tracer.trace,test=develop

* test=develop, fix docker with paddle nccl problem

* test=develop, add ut for debug string and gradient_accumulator

* test=develop, add tests for layer/gradient_accumulator/prepared_op

* test=develop, fix complie error for test_prepared_op

* test=develop, add more ut for dygraph

* test=develop, create API.spec for dygraph api change

* optimize grad maker; test=develop

* optimize grad maker

* test

* grad make optim; test=develop

* fix unittest bugs; test=develop

* add dygraph grad op maker and split_op

* grad op maker refactor; test=develop

* add dygraph grad maker; test=develop

* fix op deformable_conv_v1_op bug; test=develop

* fix deformable_conv prroi pool bugs;

* fix new op grad op maker bug; test=develop

* fix split by ref bug; test=develop

* fix dygraph auto prune bug; test=develop

* fix test_trace bug; test=develop

* fix fused emb seq pool bug; test=develop

* remove useless code in op_desc file; test=develop

* remove useless code, StrVarBaseNode; test=develop

* fix review issues; test=develop

* fix rank_loss grad maker; test=develop

* remove flag in VarBase; test=develop

* fix distributed_notify_op compile bug ; test=develop

* fix reshape op double grad; test=develop

* fix expand as op; test=develop

* add impertive type_defs.h for demo_train; test=develop

* fix inference lib cmake; test=develop

* fix inference lib; test=develop

* fix infernce_lib; test=develop

* fix inference cmake; test=develop

* fix inference lib; test=develop

* fix inference lib; test=develop

* remove condition dygraph grad maker, modify local name; test=develop

* fix split grad maker bug; test=develop

* fix pyramid_op bug; test=develop

* change travis time out limit; test=develop

* restore travis; test=develop

* change timeout limit; test=develop

* support dump param to afs
test=develop

* code style
test=develop

* code style
test=develop

* dump param
test=develop

* dump param
test=develop

* dump param
test=develop

* dump param
test=develop

* Refine the cache of program, context and scope in executor.
test=develop

* Refine the unittest test_executor_and_use_program_cache.

* Add the test the PaddingRNN with use_program_cache=True.
test=develop

* Remove a check.
test=develop

* Refine the unittest to check whether it is correct when setting use_program_cache=True.
test=develop

* fix jit_matmul bug 

* update jit matmul and add test

* Move the codes of fused operators to operators/fused directory.
test=develop

* Correct the op name in cmake.

* Change the use of PADDLE_ENFORCE.
test=develop