* Implement a common PointerArray.

* Polish codes.

* Add including of header file.

* Add the branch of kFix8.

* Fix compiling error.

* Add alignas hint to fix the performance drop.

* Optimize the H2D copy in stack_grad.

* Rename the macro.

* Fix align hint for different compilers.

* Polish the define of PADDLE_ALIGN.

* Fix compiling error.

* Remove the align hint on windows.