swift234

Type-check raw type of enum decls.

Allow the inheritance clauses of enums to reference a non-protocol type as their raw type. For now, only diagnose that the raw type occurs first, that there's only one raw type, that there are no circularities in raw types, like we do for class inheritance, and additionally that the raw type is literal convertible, which we'll require for the raw values of the cases.

Swift SVN r8529