* Drwebb/gpu backend dot op (#387)

* GPU Dot prod emitter switch statement

* cuBLAS dot kernel call

* Flush out arg substitution into gpu dot kernel call

* Drwebb/gpu backend dot op (#392)

* Take in CodeWriter into gpu op emitters

* Introduce GPU function gen based on pass functions

* Additional gpu emitter stubs

* link cublas in to unit test and ngraph

* Use static code gen methods for GPU, add new GPU op stubs

* use pass manager to declare functions / cublas Updates

* Prune down gpu_external_function wip

* Switch back to GPU tensor views in GPU backend

* Pass in cublas handle to GPU external function

* cuMalloc memory in gpu tensor view

* Use cuda runtime malloc and free for tensor view managment c

* change GPU tensor view init, and use GPU tensor view for GPU call frame

* include headers as system dirs

* GPU tensor printing utility function

* cublasSetPointer to device mode / Fix copyright notification lowercasing

* Passing GPU dot product test using cuBLAS

Clean up

* Changes from review

* wip

* wip

* remove get_vector from runtime::TensorView class as it was for unit test only

* cleanup

* move writting vector to runtime::TensorView to the unit test dir

* merge fix

* PR review change

* update from PR comment

* update changes file

* Add mention of blob ref of original file from caffe2

* Mention location of source listing originally from LLVM project

* Initial GPU_ExternalFunction implementation

Other changes:

Add GPU runtime to same cmake block as GPU, include CUDA headers if GPU enabled

Initial passing (a+b)*c test

Properly link cuda libraries

Simple GPUTensorView implementation

Initial GPU emitter

GPU codegen initial function gen, no kernels yet

Rename GPU emitter and tensor_view_wrapper to match naming convention

* GPU external function based on BASE

* Fix stray base -> gpu

* TensorViewWrapper -> GPU_TensorViewWrapper

* Copy over emitter from base transformer

* Fix for naming dense layout

* Copy kernel emitters from base -> gpu and strip out kernel_utils

* Add aliases to GPU_TensorViewWrappers

* More fixes for naming descriptor::TensorViews

* Move in call_frame implementation from base -> gpu

* apply code format

* GPU codegen running A+B*C

gpu emitters
gpu ctx setup cuda_module kernels
Remove GPU_CF perf counters
Use gpu kernels in external function
Add GPU 1d dot test

Review Changes:
* Remove CPU specific kernel emitting method bodies

* Use copy_data from test/util.cpp, uncomment compileTest

* Use test_utils copy_data function

* Grab function name from pass manager for def, clean up indentation

* Simple boilerplate for GPU runtime files

  - GPUBackend
  - GPU ExternalFunction
  - GPUManager
  - GPUCallFrame

* Test for construction all GPU runtime classes

* Comment out calls, constructors haven't been defined

* Clang CUDA source example to later test compiling

Clang cuda example from:
https://gist.github.com/anonymous/855e277884eb6b388cd2f00d956c2fd4

* Initial nvptx compiler copied from CPU compiler sources

* Define FunctionMap and Instruction for gpu external function

* Rename Compiler -> NVPTXCompiler for gpu compile. Add call to compile for test

* Rename StaticCompiler -> NVPTXStaticCompiler for GPU code gen

* CAdd nvptx_compiler and nvptx_execution_engine to gpu sources

* Compiling source unit test using hardcoded PTX

* (a+b)*c test for GPU

* WIP Fix compile

* rmed accidentally included file

* Fix compile, and LLVM link errosr from nvptx_compiler.cpp

* Stub out parts needed for GPU manager

* Test GPU runtime method stubs

* Cleanup

* Add GPU runtime to same cmake block as GPU, include CUDA headers if GPU enabled

* Kill reflexive assertion

* change GPU naming convention to match CPU

* Snake case functions and identifiers in test case

* Change element type to match changes in master

* Make CUDA headers accessible for codegen with GPU transformer

* clang-format

* apply-code-format

Clang cuda example from:
https://gist.github.com/anonymous/855e277884eb6b388cd2f00d956c2fd4