Optimize the concat and split cuda implementation for cases when the number of inputs/outputs is less than 5. (#17979)

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Optimize the concat and split kernel for specical cases when the number of inputs/outputs is 2 (#17415)

* Optimize the concat and split kernel for special cases that the number of inputs/outputs is 2.
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* Refine codes.
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* Correct the condition.
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* Move the define of tmp_data outside the if statement.

* Print the cudnn minor version.
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* Fix the case when in_num/o_num is 1 in concat/split op.
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* Remove const_cast.
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* refine tensor
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* refine tensor
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* fix device_context log
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* Add Temporal Allocator

* add Temporay Allocator to DeviceContext
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* code refine
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* fix mean_iou
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* Add DeviceTemporaryAllocator
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* fix conv_op bug
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* small fix
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* code refine
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* log refine
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* fix unit test
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* move double check

* refine concat_and_split
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* add limit_of_temporary_allocation
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* fix name
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* speedup split_op
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* speedup split_op
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* rename ConcatGrad to Split

* refine concat and split
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* fix compile error

* Make the CUDA kernel of concat correct and fix unit tests.

* Fix CPPLint issues in lstm_cpu_kernel.h

* Fix CPPLint issues in math/math_function_test

* Fix CPPLint issues in math/math_function_test

* Fix CPPLint issues in math/concat.cc

* Fix CPPLint issues in math/concat.cc

* Fix CPPLint issues in math/concat.cc

* Fix CPPLint issues in math/gru_cpu_kernel

* Fix CPPLint issues in math/selected_rows_functor_test.cu

* Fix compile error

* Fix compile error

* "re-commit "

* "picked up"

* "fix ci"

* "fix pdb hang up issue in cuda 9"