[clang] [AIX] Turn on `#pragma mc_func` check by default (PR #101336)

[Qiongsi Wu via cfe-commits]

qiongsiwu wrote:

https://github.com/llvm/llvm-project/pull/102919 is created to revert this feature now. I will review our discussion and consider an improved implementation. Thanks again for the input and discussion! 

https://github.com/llvm/llvm-project/pull/101336