[code-reflection] Integrated: Finally found and fixed cuda side CUstream bug

[Gary Frost]

Finally tracked down (and fixed) CUstream CUDA backend bug, which was halgting ability to minimize buffer copies. 

This checkin also includes a pure native raw opencl-squares and cuda-squares example code (no Java at all but using the ffi backend hooks to execute OpenCL/CUDA from native code)

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Commit messages:
 - Finally found and fixed cuda side CUstream bug

Changes: https://git.openjdk.org/babylon/pull/380/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=380&range=00
  Stats: 79 lines in 8 files changed: 22 ins; 0 del; 57 mod
  Patch: https://git.openjdk.org/babylon/pull/380.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/380/head:pull/380

PR: https://git.openjdk.org/babylon/pull/380