swift234

[Mangler] Introduce a 'Qq' mangling format for archetypes that will be
used only for debug info and within the _Tt namespace.
The DWARF output created by swift is intentionally flat, therefore
archetypes need to be emitted with their DeclContext. While increasing the
length of the mangled names in some cases (substitutions help a lot) it
has the advantage of making names completely self-contained.
There is a lengthy thread on swift-debugger discussing this change.

Swift SVN r10348