The presence of a deinitializer will eventually indicate whether a class's deinitializer is non-trivial for non-resilient modules. Also improve recovery for normal source files for various bad ways of declaring a deinitializer.
We're going to do need to do more here for inlinable accessors, which /do/ have bodies, but this helps us get to a bare minimum testing configuration.
And test this by tweaking the rules to allow functions without definitions, like SIL files.
