* Force-inline implementations. They pass around pointers to shared memory
blocks. Without inlining compiler must operate via generic pointers.
Inlining allows compiler to detect that we're operating on shared memory
which allows generation of substantially faster code.
* Fixed a long-standing typo which resulted in launching 8x more kernels
than we needed (.z dimension of the block is unused by the kernel).
Also, a few minor fixes for GPU tests running in HIP mode.
1. Adding an include for hip/hip_runtime.h in the Macros.h file
For HIP __host__ and __device__ are macros which are defined in hip headers.
Their definitions need to be included before their use in the file.
2. Fixing the compile failure in TensorContractionGpu introduced by the commit to
"Fuse computations into the Tensor contractions using output kernel"
3. Fixing a HIP/clang specific compile error by making the struct-member assignment explicit
The major changes are
1. Moving CUDA/PacketMath.h to GPU/PacketMath.h
2. Moving CUDA/MathFunctions.h to GPU/MathFunction.h
3. Moving CUDA/CudaSpecialFunctions.h to GPU/GpuSpecialFunctions.h
The above three changes effectively enable the Eigen "Packet" layer for the HIP platform
4. Merging the "hip_basic" and "cuda_basic" unit tests into one ("gpu_basic")
5. Updating the "EIGEN_DEVICE_FUNC" marking in some places
The change has been tested on the HIP and CUDA platforms.
