[flang] [llvm] [flang-rt] Fixed warnings and miscompilations in CUDA build. (PR #134470)

[Valentin Clement バレンタイン クレメン via llvm-commits]

https://github.com/clementval approved this pull request.

LGTM! Thanks for fixing the warnings 

https://github.com/llvm/llvm-project/pull/134470