[clang] [clang][ASTImport] fix issue on anonymous enum import (PR #93923)

[Balázs Kéri via cfe-commits]

https://github.com/balazske commented:

Does this work on the following code?
```
     struct A {
        enum { E1,E2 } x;
        enum { E3,E4 } y;
      };
 ```

https://github.com/llvm/llvm-project/pull/93923