SIL verification was failing for modules containing functions with `@_backDeploy` because `SILSkippingChecker` expected the `SILFunction` corresponding to the resilient copy of back deployed function to be empty. Since the overall function declaration for a back deployed function is considered inlinable, the body will be typechecked and SILGen emits both the fallback copy of the function and the resilient copy of the function. The checker should therefore expect to see back deployed functions that are not marked as serialized.
