swift234

SILGen: Don't pretend to handle ObjC APIs that "lie" about block return optionality.

If an ObjC API claims to return a nonnull object of a bridged type, such as blocks, then we're already screwed since we don't take that possibility into account when bridging to a Swift function. Attempting to peephole that case only generates broken code attempting to bitcast () -> () to Optional<() -> ()>, which is invalid due to the abstraction change between () -> () and Optional<T>. Fixes SR-2331.