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

[Tony Varghese via cfe-commits]

tonykuttai wrote:

> @tonykuttai, for future reference, it is easier for reviewers to do incremental reviews if force pushes are avoided on the PR branch.
> 
> Note also that for [9c2b2fe](https://github.com/llvm/llvm-project/commit/9c2b2fe99ea56670e01dfce24c25ddbbfd0392c9), the commit message for the squashed commit is out-of-date due to changes made during the PR review process.

Unfortunately, due to the merge commits in between we might need a squashed-commit with forced push to clean the commits now.

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