*-sys crate design

[termoshtt]

FFI crate separation, e.g. cuda-sys, cudart-sys, and cublas-sys has benefit

• to separately link to libcuda.so, libcudart.so, libcublas.so
• to better support cargo feature gates disccused in Cargo features for CUDA version (updated Dec. 10) cuda-sys#5

How to split?

• cuda-sys
  • FFI for CUDA Driver API (libcuda.so)
• cudart-sys
  • FFI for CUDA Runtime API (libcudart.so)
• cublas-sys
  • FFI for cuBLAS
• cufft-sys
  • FFI for cuFFT

and so on.

[termoshtt]

Moved: rust-cuda/cuda-sys#9