#dbugfix: Unclear error message when trying to inherit from multiple classes

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class Test: Foo, Bar, Baz
{
}

class Foo {}
class Bar {}
class Baz {}

Error: class `Test` base type must be interface, not Bar
Error: class `Test` base type must be interface, not Baz

I thought this error message used to be a lot better; along the 
lines of "D does not support multiple inheritance. Use interfaces 
instead." It'd be nice if it was changed to be clearer about what 
the error is.

https://issues.dlang.org/show_bug.cgi?id=18574