swift234

[Clang importer] swift_newtype with bridged computed rawValue

For swift_newtype structs that we create, we sometimes need to provide
a bridged type interface. In these cases, we use the original
non-bridged type as an underlying stored value, and create a computed
rawValue of bridged type. We similarly create an init() taking the
bridged type, and cast it appropriately to/from storage.

Tests updated.