swift234

Restore the original intent of our IRBuilder to not provide
functions to create load/store instructions without alignment.

Fix a couple of places that were unnecessarily using this.
This includes patching up some very suspicious code for generating
"shadow copies" of explosions for debug info that's not using
the existing TypeInfo-based load/store facilities for some
reason; I left the existing pattern in place for now, but it's
probably bogus.

Swift SVN r29459