Make type qualifiers in base class lists a parse error

[Bolpat]

Currently allowed:

class C : const(Object) { }
auto obj = new class const(Object) { };

The const does nothing, it is ignored. It should not compile to write such code.

I’m not suggesting that the following be an error:

alias Base = …; // happens to be const
class C : Base { }
auto obj = new class Base { };

That might break some code (e.g. if the alias is to a typeof) and the fix might be both annoying and non-trivial. However, if const is lexically in the source file, the fix is to simply remove it. In all likelihood, such code does not exist because, again, the qualifier is ignored.