Unused private field is not marked as unused if it's annotated

Relevant issues:
* https://github.com/eclipse-jdt/eclipse.jdt.core/issues/1052
* https://bugs.eclipse.org/bugs/show_bug.cgi?id=547451#c24

If ECJ is configured to warn about unused fields, it does not do so if the field is annotated (at least for some annotations).

For example, using Lombok:

```java
class My {
@NonFinal // https://projectlombok.org/api/lombok/experimental/NonFinal
private int resultDebt;
}
```
the field is not marked as unused even though it should be.

Start by reproducing the ECJ unused-field warning with the annotated Lombok @NonFinal example and trace the compiler's unused-field analysis. The fix is done when annotated fields that are never used are reported appropriately, while the relevant annotation behavior remains correct.

Written by the indexing model from the issue text.