The problem here was when we do cycle detection, we tried to look
at the source of the candidate constructor that we are looking at
delegating to. If we are in a cross-language case, the target might
be from metadata via the skeleton reference and we don't have source.
Rather than fixing the code that assumes it's a source method, I'm
making a change that says if the constructor you're delegating to is
in the base type, then we can't create a cycle and can skip the check
entirely.