It turns out that implementing the rethrow-on-fallthrough

semantics of a ctor/dtor function-try-block catch handler
by pushing a normal cleanup is not just overkill but actually
actively wrong when the handler contains an explicit return
(which is only legal in a dtor).  Just emit the rethrow as
ordinary code at the fallthrough point.  Fixes PR13102.

llvm-svn: 158488