[Issue 19619] Temporary solution for attribute extensibility problem

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19619

--- Comment #2 from anonymous4 <dfj1esp02 at sneakemail.com> ---
AIU the problem with normal core.attributes is that dmd backend glue code has
difficulty recognizing UDAs (as if they are only for introspection).

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