Even though SO may not be correct
overrides sometimes, it feels more
natural to treat fake overrides as...
well, "overrides". And without it
we'd need to make the code in
`FirOverrideChecker` less intuitive.
- report errors on implementing methods of Any in interfaces
- update testData
~~~
Java 8 override restrictions: interface can't implement a method of 'Any'
- update compiler sources