Close https://github.com/llvm/llvm-project/issues/73023
The direct issue of https://github.com/llvm/llvm-project/issues/73023 is
that we entered a header which is marked as pragma once since the
compiler think it is OK if there is controlling macro.
It doesn't make sense. I feel like it should be sufficient to skip it
after we see the '#pragma once'.
From the context, it looks like the workaround is primarily for
ObjectiveC. So we might need reviewers from OC.
