[clang] Run PreStmt/PostStmt checker for GCCAsmStmt (PR #95409)

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T-Gruber wrote:

> > > Thanks for the ping. Looks really nice! FYI I just came across a case last week w.r.t asm gotos. You can have a read [here](https://sonarsource.atlassian.net/browse/CPP-5459) if you are interested in the subject.
> > 
> > 
> > Thank you! Looks interesting. Does this mean that the linked problem would also benefit from this PR?
> 
> I haven't if this PR would help or not. My guess would be that this wouldn't help.
> 
> Please fix the [formatting](https://github.com/llvm/llvm-project/pull/95409#issuecomment-2219921933). After that we can merge this PR.

I reworked the unittest and fixed the format as well. Thanks for your help!

https://github.com/llvm/llvm-project/pull/95409