[llvm] [Flang-RT] Make __cuda_builtins dependency explicit (PR #205895)

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

This breaks check-flang:
```
Failed Tests (1):
  Flang :: Semantics/cuf05.cuf
```
PR with a fix: https://github.com/llvm/llvm-project/pull/205914

https://github.com/llvm/llvm-project/pull/205895