[clang] [clang][CodeGen] Emit `llvm.tbaa.errno` metadata during module creation (PR #125258)

[John McCall via cfe-commits]

https://github.com/rjmccall commented:

To be honest, I was hoping the TBAA test-generation changes would leave us in a position where we *didn't* have a bunch of spurious changes to tests just because something unrelated perturbed the metadata order. It's great for readability that the metadata match variable includes the name of the type now, but the fact that it still includes a number means that this PR still has to have a bunch of changes renaming e.g. `CHAR_TBAA2` to `CHAR_TBAA6`.

https://github.com/llvm/llvm-project/pull/125258