swift234

SIL: Fix self cleanup with self.init() delegation

When we take the self value out of the box inside a
RebindSelfInConstructorExpr, zero out the box right away
instead of doing it right before the apply or try_apply
instruction.

This way, if we have to emit a try_apply while while
evaluating arguments, we don't double-free the self
value.

Also, teach DI about releases of loads from the self box,
since now we might release the uninitialized self this
way.

This change also lets us get rid of some weird code.

Progress on <rdar://problem/21991742>.

Swift SVN r31141