[runtime] Don't assert in mono_class_is_assignable_from on iface gtd

[runtime] Don't assert in mono_class_is_assignable_from on iface gtd

Don't assert when comparing if an "array special interface" is assignable from
an array.

The code assumed that the special interface is some sort of generic instance
like ``IList`1<string>``, but it could be a generic type definition
``IList`1``.

There is a case where we would be obligated to return TRUE:
If someone used reflection to get the generic param of ``IList`1`` and then made an
array:
```
   var i = typeof (IList<>);
   var iparam = i.GetTypeInfo().GenericTypeParameters [0]; // returns gparam T
   var a = iparam.MakeArrayType (); // T[]

   Console.WriteLine (i.IsAssignableFrom (a));
```

But that case is handled by the `MONO_CLASS_IMPLEMENTED_INTERFACE` check,
earlier in mono_class_is_assignable_from.

So we can return FALSE here.

Fixes https://github.com/mono/mono/issues/7095