[clang] [llvm] [PowerPC][AIX] Support #pragma comment copyright for AIX (PR #178184)

[Tony Varghese via cfe-commits]

tonykuttai wrote:

The following tests had to be modified as we are keeping the `LowerCommentStringPass` in both `PassBuilder::buildO0DefaultPipeline` and `PassBuilder::buildModuleOptimizationPipeline`. 
```
Failed Tests (6):
  Clang :: CodeGen/lto-newpm-pipeline.c
  LLVM :: CodeGen/AArch64/print-pipeline-passes.ll
  LLVM :: Other/new-pm-defaults.ll
  LLVM :: Other/new-pm-thinlto-postlink-defaults.ll
  LLVM :: Other/new-pm-thinlto-postlink-pgo-defaults.ll
  LLVM :: Other/new-pm-thinlto-postlink-samplepgo-defaults.ll
```

https://github.com/llvm/llvm-project/pull/178184