swift234

Fix MemoryBehavior on SIL instructions that have a CastConsumptionKind.

Having the wrong memory behavior here can cause SIL Code Motion to move
retains and releases across these instructions, which is invalid.

This resulted in a retain-after-free issue in the DollarChain benchmark
after I committed r23673 (which was soon after backed out in r23679).

Swift SVN r23722