swift234

IRGen: Always use swift_initClassMetadata_UniversalStrategy() even if the class does not have generically-sized fields

This function points the ivar offsets at per-metadata field offsets
before passing off the class to the Objective-C runtime, ensuring
we don't slide the global ivar offsets multiple times.

The swift_initializeSuperclass() function does not do this ivar
cloning, so it cannot be used for generic classes even if they do
not have generically-sized fields.

An alternative would be to refactor the runtime to clone ivar offset
vectors in swift_initializeSuperclass(), but this doesn't seem to be
worth it for now.