swift234

IRGen: Fix generic member of generic type mangling

The mangler was incorrectly walking the full generic param list chain and panicking when mangling nested generic methods because it saw the same archetypes redefined. Since the outer archetypes had to have been mangled as part of the outer context, the deep walk shouldn't ever be necessary.

Fixing this allows you to successfully define a generic method of a generic type; however, you can't call one yet because CallEmission, CalleeSource, and Callee need to learn how to aggregate multiple substitution lists.

Swift SVN r3935