@deprecated on a class is ignored

```scala
@deprecated("bla", "2.11.0") class Foo

object Test {
  new Foo
}
```
```scala
% scalac -deprecation try/depr.scala
try/depr.scala:4: warning: class Foo is deprecated (since 2.11.0): foo
  new Foo
      ^
one warning found
% dotc -deprecation try/depr.scala
%
```