[clang] Suppress octal literal diagnostics from system macros (PR #192481)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> > If you're okay with that, I can file an issue as a Task so we don't lose track of the idea.
> 
> Sure, but also add a fixme in the code - it's probably the only place we do that in Clang and that might be confusing to whoever look at that code next

I filed it as https://github.com/llvm/llvm-project/issues/192490 thank you for the suggestion!

https://github.com/llvm/llvm-project/pull/192481