swift234

Fix <rdar://problem/22723281> QoI: [DI] Misleading error from Swift compiler when using an instance method in init()

When a root class delegates to a non-class-bound protocol method, the self value
gets wrapped up in a SIL alloc_stack so it can be passed by address.  Recognize
that the store involved is doing this, so we can provide a more specific diagnostic.

Before this, we produced:
variable 'self.x' used before being initialized

Now we produce:
error: use of 'self' in method call 'getg' before all stored properties are initialized
note: 'self.x' not initialized