This PR added basic support for 'return' grammar in dy2stat. It supports the control flow of 'return'.

The basics idea is using a return value variable to store the early return statements and boolean state variables with if-else to skip the statements after the return statements.

**This PR is very basic support. There are some corner cases I didn't develop/test**. For example, 'return None', 'return different length of variables', 'return non-tensor and tensor together', 'no return statement'. **These corner cases will be done in my next PRs**. Target date is this week.

**Note**: 
1. for the unit test, I changed test_program_translator.py because the StaticCode of `dyfunc_with_if_else` will change. To guarantee the correctness of `dyfunc_with_if_else`, I also run it in `TestRecursiveReturn` in test_return.py.

2. I commented the early return code in bert_dygraph_model.py because 'return different length of variables' is unsupported now. I also know that there are some other models used early return and we didn't enable it in the unit test. I will add support for it in next PRs and then re-enable those tests.

* fix beam_search infershape, test=develop

* fix beam search op unittest, test=develop

* add default cudnn lib path, test=develop

* change default path in func, test=develop

* move to linux branch, test=develop

* fix var error in other plat, test=develop

* add cycle_gan_model

* align train test=develop

* modify image_size into 64 to avoid TimeOut test=develop

* TODO in GPU test=develop

* refine PADDLE_THROW, test=develop

* refine error msg, test=develop

* refine cuda error, test=develop

* follow comments, test=develop

* fix compile problem, test=develop

* fix bug, test=develop

* test=develop fix conv3d_transpose_test error

* Refactor of conv fp32 oneDNN operator
test=develop

* Formatting fix
test=develop

* Return Enforces
test=develop

* GetWeights improvements
test=develop

* Paddle-TensorRT support slim QAT. test=develop

* add comments. test=develop

* use RenameInput instead of ResetInputs. test=develop

test=develop

* generate dummy file using cmake configure_file function to avoid re-generating it. test=develop

* add cmake/dummy.c.in. test=develop

fix sample code error of fluid.dygraph.NaturalExpDecay

* remove disable profiler_test on win32

* add log

* enlarge the elapsed time

* Revert "add log"

test=develop

* don't re-generate header file if content doesn't change. test=develop

* add copy_if_different function. test=develop

* Refine caches of converting func test=develop

* fix if statement test=develop

* refine cache code test=develop

* rm unuse import statement test=develop

* Polish code comment test=develop

* Refine check_type for @declarative test=develop

* add new api (set_global_initializer/reset_global_initializer),test=develop

* add new api (set_global_initializer/reset_global_initializer),test=develop

* fix doc and example code of set_global_initializer,test=develop

* add for iter var list, test=develop

* add enumerate unittest, test=develop

* Start implementing int8 eltwise add

test=develop

* - Fix to Michal PR

* - Fix

test=develop

* - Lint fixes

test=develop

* - Added checking if elementwise_mul can be used

test=develop

* - Added attribs to skip_attrs_set

test=develop

* - Improved broadcasting

test=develop

- fixes to compilation

- fix

- fix

- Lint fixes

test=develop

* - removed redundant condition

test=develop
Co-authored-by: NMichal Gallus <michal.gallus@intel.com>

test=develop

* add relu for lenet, test=develop

* fix test model, test=develop

* The arg of append() can be not Tensor temporarily.

* Add Seq2Seq as ProgramTranslator Unit Test. 

* set dtype of vocab_size_tensor to int64 to pass Windows-CI. 

* fix bug of prelu when rank not equal 4, test=develop

* fix prelu inference, test=develop

* fix api, test=develop

* fix shape when mode is chennel, test=develop

* remove debug code, test=develop

* add unittest, test=develop

* blockReduce opt

* launch threads align to warpSize

* reduce unnecessary shared memory for broadcast reduced value

* vectorize SoftmaxKernelWithEltadd

* add fp16 constrain

* test=develop

As the title

* Add a StatValue class in the backend to represent a stat.
* Add a singleton StatRegistry to maintain the collection of stats.
* For the sake of code neatness, we only support type of int and float, which can cover most of the scenarios.