[clang] [Clang] Implement P3034R1 Module Declarations Shouldn’t be Macros (PR #90574)

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yronglin wrote:

> > It would be nice to have a reproducer. I can't tell the root cause from this error, so I can't use it to strengthen the current tests.
> 
> I intend to provide a reproducer. I just can't do it today. So don't wait on it as a justification to avoid reverting.

The PR has already been reverted before this, and no one is avoiding reverting it.

https://github.com/llvm/llvm-project/pull/90574