Adding ANNOTATION_DEF to the valid list of parentASTs for SuppressWarningsHolder.

Without this, any @SuppressWarnings (checkstyle or not) present on an annotation definition class will fail if the Holder is added as a module.

For instance,
@SuppressWarnings("PMD.VariableNamingConventions")
public @interface PathPartUri {
    //...snip...
}

This will fail without the ANNOTATION_DEF TokenTypes.

[ERROR] PathPartUri.java[0:n/a] Got an exception - java.lang.NullPointerException
[WARNING] PathPartUri.java[20:1] suppress.warnings.invalid.target