[clang] [clang][ExtractAPI] Stop dropping fields of nested anonymous record types when they aren't attached to variable declaration (PR #104600)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-quick` running on `linaro-clang-aarch64-quick` while building `clang` at step 4 "build stage 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/3004

Here is the relevant piece of the build log for the reference:
```
Step 4 (build stage 1) failure: 'ninja' (failure)

```

https://github.com/llvm/llvm-project/pull/104600