The after-defer test jumps to a deferreturn site.  Some functions
(those with infinite loops) have no deferreturn site.  Add one
so we have one to jump to.

Change-Id: I505e7f3f888f5e7d03ca49a3477b41cf1f78eb8a
Reviewed-on: https://go-review.googlesource.com/14349Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>