swift234

fix <rdar://problem/20563234> let-else problem: cleanups for bound patterns shouldn't be run in the else block

We were previously emitting the 'else' block on a let-else after emitting the patterns bound, which
would cause cleanups for the bound patterns to be run on entry to the else.  This doesn't make sense
because those have already been torn down by the failure path in the conditional pattern binding.

Fix this by emitting the 'else' code up front, before any of the patterns are bound.



Swift SVN r27451