swift234

Revert "Fix the closure specializer's handling of indirect result types."

This reverts commit 2cba2a400037431e787a1422a6a5bb1a65433037.

I'm speculatively backing this out because the builds are in terrible
shape and I can't tell if this caused an issue.

I can't easily verify because my builds are now breaking for a
different reason.

Swift SVN r24272