[code-reflection] Integrated: More C99 code gen fixes

[Gary Frost]

Fixes missing semicolon at end of struct  which  broke CUDA backend.

Removed extra '\n' at the end of generated  forLoop() 

Previous fix aggressively impacted all users of semicolonNlSeparated().   

Moved primitive typecheck to OpTk

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Commit messages:
 - More C99 code gen fixes

Changes: https://git.openjdk.org/babylon/pull/743/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=743&range=00
  Stats: 27 lines in 6 files changed: 15 ins; 3 del; 9 mod
  Patch: https://git.openjdk.org/babylon/pull/743.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/743/head:pull/743

PR: https://git.openjdk.org/babylon/pull/743