swift234

Now that definite initialization is exploding copy_addrs, the simplistic
algorithm used by inout deshadowing broke in many common cases.  Reimplement
the pass with a different approach, where it looks for autogenerated copies
into and out of the inout pointer, which may be exploded.

This doesn't handle nontrivial types yet, but is progress towards fixing
rdar://15228172.



Swift SVN r9702