swift234

Add ClangImporter results to dynamic class member lookup.

Caveats / TODOs:
- Since we're using the global method pool, this isn't scoped by module.
  We could do a per-module filter, but I don't know if that will actually
  buy us much.
- Clang's method pool does not include methods from protocols.
- This requires importing every single method found into Swift's AST just
  to print them in the completion results.

Swift SVN r7329