Currently jextract throws an UnsopportedOpperationException when encountering a type that has a flexible array member.

As a result of that no class is written for the type, and when loading the enclosing interface this throws a NoClassDefFoundError, prohibiting use of the entire header interface.

We could mitigate this problem by emitting an undefined layout reference instead of throwing an exception, which would only make the type with the flexible array unusable, but still allow other things in the same interface to be used.