swift234

Teach alloc_box promotion to insert a destroy_addr and dealloc_stack instruction
at the end of a variables lifetime.  Right now, this is only handles the most
simple case, but it should be conservatively correct now.

This also inserts destroy_addr instructions even for trivial instructions.  If
there is a way for SIL passes to query a SILType for triviality, this can be
easily fixed.


Swift SVN r6422