decl context of the type alias.
This implements <rdar://problem/15290346> "typealias sugar needs to be
mangled into debug info mangled type names".
Swift SVN r10749
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
Produce protocol descriptors when we see a protocol definition in the current module. If the protocol is @objc, go through the existing path for generating full Protocol* metadata for objc objects; otherwise, emit our layout-compatible but strong-external-linkage Swift protocol descriptor record.
Swift SVN r9867
