enable mkldnn_concat layer

remove usused ProtoDataProvider related codes

add option WITH_MKL 

Add padding for conv_transpose_op

Fix no framework proto file

mkldnn only need one trainer

* Support the build for multiple architectures at one cmake command (iOS).

* Update the documentations.

The pool_limit_size need be zero in mobile inference.

fix a lot of warnings -Wunused-but-set-variable and Wunused-variable when compile openBlas

Fix cos_sim_op in debug mode.

Fix bilinear_tensor_product_op in debug mode.

* first commit

* Python API for while op

* Python Unittest for simple while_op forward

* fix out to be list

* Fix UT

* VarType

* Fix several bugs

* Fix bug

* Fix bug

* Fix Bug

* Fix bug

* Fix unittest

* Remove debug log

* Add comments

* add PADDLE_ENFORCE

* while_grad_op first commit

* Add `BlockDescBind::FindRecursiveOrCreateVar()` and fix bugs

* not sure how to setdim of while outputs

* push for test

* add executor vlog

* fix bug of while_op cond

* Several enhancement for code

1. Backward always infer shape & infer var type. Since there are RENAME
variables will be created when creating backward operator, but their
shape & var types are not inferenced.
2. Never use SomePtr-> directly, since every pointer could be nullptr if
it is a function return value. Add `detail::Ref` to cast pointer to
reference safely.
3. Enhance error message for backward.
4. Infer data type of variable in `sum` and `tensor_write`

* Fix bugs of while_op gradient

* Fix several bugs of while_op grad

* fix fill zeros like

* fix 3 >= 3

* fix place holder shouldn't be null

* fail on sum op

* Fix SumOp of TensorList

* clean up

* pass while test

* fix test_array_write_read

* pass sum op

* Support int/int64 for fill_constant_batch_size_like

* Fix compile

Fix crashes due to multiple calls to paddle_init

auto set cpu env when mkldnn or mklml enabled

Update annotations of layers.py.