[clang] [clang] Fix unexpected warnings after a01307a (PR #75591)

[via cfe-commits]

https://github.com/mikaelholmen commented:

I really don't know this, and I have no easy way to test that this really fixes all the new warnings we see with a01307a6ee788, but at least it seems to fix the added cases in the missing-field-initializers.c test so it's at least seems to be a step in the right direction.

https://github.com/llvm/llvm-project/pull/75591