[clang] [llvm] [OpenACC] Switch Clang to use the Flang 'appertainment' rules for cla… (PR #135372)

[Erich Keane via cfe-commits]

erichkeane wrote:

Updated list:

```
Disagreements on 'num_gangs' appearing >1x on kernels/kernels-loop (justification for kernels-loop should apply to kernels as well?) (UNK way forward right now)
    Clang :: SemaOpenACC/compute-construct-num_gangs-clause.c
  
FLANG: prohibits device_num >1x  (UNK way forward RN).
  Clang :: SemaOpenACC/init-construct.cpp
  Clang :: SemaOpenACC/shutdown-construct.cpp
  
Disagreement on 'bind' on a 'routine'. (UNK way forward right now)
   Clang :: SemaOpenACC/routine-construct-clauses.cpp
```

https://github.com/llvm/llvm-project/pull/135372