[code-reflection] Integrated: converging cuda/opencl code gen using preprocessor

[Gary Frost]

Took opportunity to move more c99 code gen to preprocessor.

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Commit messages:
 - converging cuda/opencl code gen using preprocessor

Changes: https://git.openjdk.org/babylon/pull/602/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=602&range=00
  Stats: 79 lines in 3 files changed: 20 ins; 25 del; 34 mod
  Patch: https://git.openjdk.org/babylon/pull/602.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/602/head:pull/602

PR: https://git.openjdk.org/babylon/pull/602