[clang] [Clang][OpenMP] Fix stdio.h wrapper when glibc includes again (PR #77017)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 approved this pull request.

TYVM for fixing this. There's a lot of hacky stuff we need to do here to make it work, but it is what it is.

Guessing the other wrapped files are fine? I remember having problems with `cytype` and `string` but I hopefully resolved a lot of those already.

https://github.com/llvm/llvm-project/pull/77017