swift234

[closure-spec] Teach closure specialization to not specialize closures with indirect return and re-enable it.

It is possible to teach the closure specializer to handle these cases but given
where we are in the schedule it makes no sense to try to teach the optimizer how
to handle it.

Keep in mind though that we *will* handle the case where the function being
passed the closure has out parameters. This means that generic functions like
reduce will still be able to be specialized if the closure being passed in does
not have generics in it at the AST level. This implies that we will not handle
specialized closures with indirect results either which is unfortunate.

Swift SVN r22126