[Issue 20678] Integral deprecation should not trigger on valid code

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20678

--- Comment #2 from Mathias LANG <pro.mathias.lang at gmail.com> ---
Reduced example:
```
immutable ushort X = ~ushort.max;
```

I'm sorry but if "the rules" dictate that the above code must trigger an error,
those rules are wrong.

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